Earthworms and their Allies

REGIONS OF

the globe. And in making this general census we shall not take into consideration the purely aquatic forms, but shall limit ourselves to the earthworms, sensu stricto, or Megadrili

and a mere variety to another. Thus it will be impossible to give a summary of the facts to be enumerated presently, which will be either

receive careful consideration on a later page. Such forms are therefore, in those cases at any rate where the evidence seems to be overwhelming, withdrawn from the list. In o

be divided for the present purpose into three divisions, viz. South Americ

one species is known from the area, Periscolex with one species, Anteoides with two species, Pontoscolex one species. Opisthodrilus with two species, Rhinodrilus (including either as synonyms or as sub-genera, Thamnodrilus,

of genera and a much larger number of species. Of a second sub-family of Geoscole

es occur within the area now under consideration. The bulk of thes

ten species, of Microscolex two spe

curs in this Continent and the following

, of which two at least are found elsewhere, and

with ten species, Ocnerodrilus (with sub-genera Liodrilus, Ilyogenia and Haplodrilus)

istributed in some 19 genera. But of these a few species (e.g. Onychochaeta windlei, Kerria macdonaldi) stray into neighbouring regions, i.e. the West Indies and California. It is

cept in the case of Onychochaeta windlei, Glossoscolex peregrinus) are distinct; these genera are

Dichogaster, Kerria and Ocnerodrilus. But with the exception of Hesperoscolex, which seems to belong rather to Central America and the West Indies, Microscolex and Pontoscolex which are world-wide and whose original home

rhinus, Fimoscolex, Enantiodrilus, Notiodrilus, Chilota, Yagansia and Kerria are at least very distinctive of S. America an

ra of earthworms which inhabit this quarter of the globe it must be premised that the facts relate only to Africa south of the Sahara. But little is known of the genera which occur in Algeria

esumably its real home is Africa. This family is known as the Eudrilidae though by some it is only regarded as a sub-family of the Megascolecidae. In this family we have the following genera: Eudriloides with 11 species, Platydrilus with 11 species, Megachaetina with two species, Reithrodrilus with one, Stuhlmannia with five species, Notykus and Bogertia with one species each, Metadrilus also with but one species, Pareudrilus with perhaps five, Libyodrilus with one and Nemertodrilus with two species, Metschaina with two spe

h America, and the common and widely spread D. bolavi which has even made its way to Europe. Of the sub-family Ocnerodrilinae we have the genus Gordiodrilus with seven species, a genus which also occurs in Madagascar and the West Indies: Nannodrilus wi

s. We next have to deal with the Geoscolecidae, of which a sub-family, Microchaetinae, is mainly found in Africa, the rest being found in the neighbouring Madagascar and some few in the East. Microchaetus contains about 14 species, Tritogenia perhaps three, Callidrilus two

Africa but are either more abundant elsewhere or (as in the case of Chilota and Notiodrilus) are equally distinctive of other parts of the world. The number of species may be estimated at 270,

ses it, for its lemurs, peculiar Insectivora and Carnivora, and above all by reason of the absence of the prevalent African types such as antelopes, zebras, rhinoceros

state of affairs which is paralleled b

our species of the genus Notiodrilus, with which perhaps Maheina braueri from th

eption, are forms which occur elsewhere and are often indeed very widely distributed 'peregrines,' so that it is hardly permissible to place them among the real i

species of Gordiodrilus occurs, and

belong exclusively to a genus of the Microchaetinae, Kynotus, which is found nowhere

only two peculiar genera, only four genera which can be re

t direct attention to the peninsula of India and adjacent parts of Burmah and the island of Ceylon

ves. We have left behind us the Geoscolecidae with the exception of the ubiquitous and clearly peregrine Pontoscolex

e sub-family Acanthodrilinae is totally unrepresented. The large sub-family Megascolecinae has very numerous representatives. Of the genus Megascolex itself there are some 30 species, of which, however, two or three are looked upon as varieties. Of the allied genus Notoscolex there are ten species and of Perionyx about 13. The genera Megascolides, Diporochaeta, Spenceriella and Woodwardia have only six species between them of which three belong to

in the region now under consideration; but it is doubtful whether they are truly indigenous. On the other hand Eudichogaster, closely allied both to Dichogaster and Trigaster, seems to be confined to this part of the world where it is represented by five species. Finally we come to the last sub-famil

ctically limited to this part of the world and consists of at least twenty species distributed among the

hich are certainly truly endemic, and which comprise between th

nce they are largely or entirely aquatic forms. Pontoscolex corethrurus, and Eudrilus eugeniae, need not detain us for reasons already amply stated. We now come to the great family Megascolecidae. Of this family the genus Pheretima stands at the head; and of the 200 or so species that have been or can be assigned to this genus all, with merely two or three exceptions, are natives of the Eastern Archipelago and adjoining mainlands of Asia. Of other Megascolecinae the region has yielded the following genera. In Java one species of Woodwardia (W. javanica) has lately been described. It is regarded by Michaelsen however as doubtfully indigenous. And the same remark may be made of Perionyx. Plionogaster, however, with four or five species, is limited, as far as our present knowledge goes, to the Phi

pecies concerning whose extraordinary powers of migration there is no possible doubt. The same may be said of Eudrilus also recorded from Australia. Here the Megascolecidae are as conspicuous as in the old world generally. We find, however, a great many members of

r Michaelsen associates Digaster, Didymogaster, Perissogaster) includes more than forty species, Fletcherodrilus has but one species, Megascolex has seventy species, Woodwardia sixteen, Spenceriella five, and Megascolides seventeen. There are four species

pecies of Ocnerodrilus and sub-genera belonging to the Ocnerodrilinae, a good many species of Dichogaster and at least one of Trigaster among the Trigastrinae, while one sub-family, that of the Diplocardiinae, is only found here and contains two genera Diplocardia and Zapotecia with quite ten species between them of which only one belongs to the last-named genus. There are no Geoscolecids (except the chiefly aquatic Sparganophilus); this family stops short in the Wes

drobaena and Allolobophora. Besides these forms, which amount to at least 130 species, we find the genus Hormogaster, with two species, the only genus of the Geoscolecid sub-family Hormogastrinae; there is also a species apiece of the genera Criodrilus and Sparganophilus (sub-family Criodri

d not from the mainland. The genus Rhododrilus with nine species is actually limited to the New Zealand group and so is an allied genus consisting of two species only, viz. Leptodrilus. This latter genus is confined, so far as present information goes, to the Auckland and Campbell islands. Dinodriloides with two species is also limited to New Zealand and to the North Island. Maoridrilus with some ten species is another native and restricted genus. So too is the allied Plagiochaeta with numerous setae on each segment but with the alternating and single nephridial pores of Maoridrilus. There are several species of Plagiochaeta of which one has been lately regarded by Dr Michaelsen as really falling within the otherwise Indian genus Hoplochaetella, while for another he has formed the genus Pereiodrilus. Neodrilus with but one species N. monocystis is an

t a complete obstacle to the existence of those Annelids; for I have myself received examples of Lumbricidae from the arctic island of Kolguev. Moreover the temperate regions would seem to be as fully populated in the way of individuals, and even of species, as are the tropical regions. Indeed as to individuals it seems that the temperate regions are more fully supplied than much of the tropics. This however is not quite the object of the present section to discuss. We are here concerned with the relative frequency of genera and species. There are according to a recent estimate of the Rev. H. Friend some forty species recognisable in Great Britain. And as already has been

partment of our subject we cannot do more than has already been done, i.e. to state the actual facts. One is tempted in comparing the rich fauna of tropical Africa with the very limited fauna of Madagascar to associate a richness of types with extent of land surface. In the two cases cited this conclusion is obvious. It may also be extended-if we confine ourselves to species and not to

nge of

only Lumbricus and its immediate allies, Helodrilus, etc., of which certain species are found to exist over wide tracts of land. There are however many genera which have a wide range and which may be contrasted with others in which the range is very limited. The two extremes are moreover connected by forms with an intermediate range. There is no doubt whatever that the genus with the widest range is Notiodrilus of which species are found throughout the antarctic region, viz., in

hough equally wide perhaps in mileage, is less impressive than that of Notiodrilus, since the land areas inhabited by the genus are continuous-almost so if we accept North America as its real habitat. Here we have a case precise

ich have a really extensive range. The only instances are Criodrilus and its ally Sparganophilus which occur in America, whether North or S

genera have very much the same range as has Dichogaster. It is to be noted however that these forms are circumtropical, and that their distribution is thus less continuous than that of Notiodrilus; they do not however show the markedly discontinuous range of certain other genera of Megascolecidae. For instance Octochaetus is well known from New Zealand, and, not occurring in the intermediate tracts, is again met with in India. Hoplochaetella is believed by Michaelsen to present us with another precisely similar instance. Then also the genera Woodwardia and Notoscolex are to be found in Australia and again (absent from the immense tract lying in between) in Ceylon. Megas

of Notiodrilus, and we shall see later that there are reasons for regarding these genera as derived fro

lly autochthonous in the countries where it occurs; and in any case it differs from Notiodrilus in occurring in Europe, where th

Plutellus the case is different and one of real discontinuity. There are however cases of wide range which is also actually continuous and such is afforded by the genus Pheretima. This genus appears to be possibly i

t, though they are not recorded from intermediate islands. Perionyx is found in Burmah, India, Zanzibar, Sumatra, and Java. There are other examples of genera which have much the same range as those enumerated. Finally there are those which are confined to one land mass and very often to a restricted region of that. Thus Kynotus is confined to Madagascar, all the genera of Eudrilidae to tropical Africa, some of

widely spread forms that have been already referred to, with the range of different g