Earthworms and their Allies
THW
d to further observations upon the geographical distribution
ows intelligible. It is universally agreed that the range in space (and in time also) of a given species of animal (or plant) is as much a part of its scientific definition as are its ana
regions may also be further subdivided. The commonly accepted regions were originally devised by Mr Sclater and are known as the Palaearctic, Nearctic, Neotropic, Ethiopian, Oriental (Mr Sclater's name was 'Indian'), and Australian. These regions were originally formed to convey the facts relative to the distribution of Passerine birds only; but it is generally held that they apply also to the distribution of vertebrates generally. The science of zoogeography does not however end with the display of
ion with the continent. Thus an identity of fauna was to be expected. On the other hand we are confronted with a very great difference between the earthworms of eastern tropical Africa and of the adjacent island of Madagascar. In the latter we have as a prevalent form the genus Kynotus; in the former continent many Geoscolecidae
erised by their earthworm inhabitants and see how far these regions agree
ich is really limited to it, and by just a few traces of other genera such as Hormogaster among the Geoscolecidae and Sparganophilus which however is possibly an accidental immigrant. This region is certainly quite clear. Now according to some persons such as Prof. Heilprin the northern part of America should
umbricidae identical with those of Europe, may possibly be also a region to be excluded in the present survey and spoken of as 'Ascolecogaea.' In the southern part of the United States we shall find genera which will be considered presently. On the other hand it is equally conceivable that this part of the world lost its earthworm fauna
hich Dr Eisen has described so many forms. On the other hand the West Indies are closely allied in their earthworm fauna to tropical South America, sharing with that region several forms of Geoscolecids belonging in both cases invariably to the sub-family Geoscolecinae. The bulk of the latter are undoubtedly tropical South American in range and there is no doubt whatever abo
the rest of America but to the world generally, there would be as I think no doubt about the practicability of making a Nearctic region. As it is, it seems to me to suit the facts of distribution better to regard the whole of the land under consideration as forming one great Neogaean region with three sub-regions, the North American, Central American and West Indian, and tropical South American. This region h
ts of the Ethiopian region according to earthworms agrees with that delimitation afforded by a consideration of other groups since it stops short at the Sahara, leaving northern Africa to be referred to the Palaearctic region. At the same time we have an analogy with South America as concerns the southern extremity of the African continent; here we meet with Notiodrilus and allied Acanthodrilinae just as in Patagonia and-as also in that quarter of the world-these forms just stray into the Ethiopian region above-specimens of Notiodrilus being met with in Madagascar as well as in tropical Africa. This bit of Africa as it appea
Megascolecinae, is, save for the mysterious occurrence of the genera Plutellus and Megascolides in America, absolutely limited to this area. Another sub-family, that of the Octochaetinae, is limited to it. So far as concerns the others of the sub-families of Megascolecidae it is only the Trigastrinae which occur here (the genus Eudichogaster and a few possibly introduced species of Dichogaster) and a scattered species or two of Notiodrilus of the sub-family Acanthodrilinae. Again there are a few and probably introduced species of the sub-family Ocnerodrilinae. More important still this region has confined to
alay archipelago. On the other hand Australia differs from the comparatively neighbouring islands of Borneo and others by the absence in those islands of the characteristic Australian genera such as Megascolex,
r from both India and Australia by the almost entire limitation of the genus Pheretima to them
and is much nearer to Australia in its earthworm fauna than is the southern island. There are, it is true, a number of genera peculiar to New Zealand, which are Rhododrilus, Leptodrilus, Maoridrilus, Neodrilus, Plagiochaeta, Pereiodrilus, Dinodrilus, Dinodriloides, but these do not represent the whole of any family or even sub-family an
ustralia, these species are but few, and the bulk of the species and of the allied genus Chilota are restricted to the antarctic quarter of the globe; they also extend all over it, that is to say in the southernmost parts of South America, in the Cape region of Africa, in Kerguelen and the Crozet Islands, and in New Zealand, as w
ensions northwards of the antarctic continent so far north as to embrace these several regions of that hemisphere. In view of the facts relating to the danger of sea water to earthworms, to their lack of facilities for migration, other than unassisted locomotion, points which have been dealt with earlier, it is difficult to explain their range in the antarctic hemisphere on other grounds. The very fact that the actual earthwo
its largely aquatic mode of life. It is also conceivable that the genus Dichogaster is another example pointing the same way. The arguments for regarding this genus as an indigene of the East are not strong. But there is on the other hand no doubt that the Indian Eudichogaster is very closely allied to it. But it is by no means excluded from this argument to suppose that these Trigastrinae owe their likeness to convergence. At any rate there are examples of equally marked convergence which seem to be as nearly proved as can be in another though allied grou
maries and glands appended to the duct, and the corresponding spermatheca, in the absence, or very slight development, of the papillae, so frequent in more specialised genera such as Pheretima, and in the general simplicity of
s on the actual facts already dealt with, it would seem that the peopling of America from Africa or of Africa from America, if it has occurred, has not taken place through Europe and the north generally. For otherwise we should expect traces of the passage. It is true that we actually have Hormogaster as a possible sign that the Geoscolecidae have passed this way. Bu
lesser group seems to indicate that no great time has elapsed since the specialisation of these different forms. The dependence of earthworms upon vegetable mould also points in the same direct
ITERATURE
ARTH
oup. To give anything like a complete list would demand many pages of titles. From the works se
neral
Morphologie der Olig
ph of the Oligocha
aeten in 'Das Thier
aphische Verbreitung
s in Suites à Bu
rms of (1)
ers in Journ. Linn. Soc.
papers in Proc. Roy.
Fauna Südwest-Austr
and and Anta
f the Subarctic Islands of New
rn. Micr. Sci. 1904, Proc. Zool. Soc. 19
. Soc. Edinb. 1891 and
)
aeta of India etc. in M
Eu
i Lumbricidi. Mem.
Af
pers in Mitth. Naturhist.
. Journ. Micr.
Am
Calif. Aca
tiis. Mem. Acc.
Ibid.,
lh. Reise, 1895 and Nacht
and by Perrier, Horst, Ude, Lankester, Stole, Pierant
N
e, 14, 78, 80,
odrilu
soma,
matidae
earthw
drilu
, 62, 85, 111
ides,
oidid
uru
9, 50, 60,
earthwo
ia, 7
n earth
chaet
haet
of earth
rilus,
rrhin
oide
eus
earthwor
dril
earthw
amilies o
earthwo
hilus,
earthw
sidrilu
osper
phor
ntin
an earth
to migr
ella, 76
mia,
nia,
stos
tia,
moirs upon e
neuron,
ura, 38
iodril
odrilus,
rilus,
od Hope, w
ogast
72, 76, 77,
redil
nd distri
io, 38,
of worms
nae, 24,
, 48, 49, 62,
obaen
, 36
aster,
haet
rodril
2, 74, 76, 80, 82, 83, 84, 92,
ogast
ster
loides,
s, 16, 55
ardia,
otre
19, 80, 84, 87
of earth
da, 5
idril
ia, 8
41, 45, 46
colex,
iodri
aeidae,
onmen
ster, 80,
, 28, 29, 61, 66,
8, 79, 82, 83, 86,
des, 27,
ster, 57
toreut
x, 76,
eus, 16
s of wo
scol
rodrilu
ter worm
laria,
, rang
al distrib
46, 59, 61, 71, 76, 79, 8
cinae, 2
x (= Glo
colex,
8, 49, 77, 79,
76, 78, 81, 92
drilu
taxid
axis,
rilus,
85, 90, 91, 10
lea
rodri
olex, 23,
olex,
ella, 80,
er, 24, 8
strinae
scol
s, 30, 75, 1
gaeo
dril
enia,
rilus,
arthworm
arthworm
, earthwo
nia,
, 18,
24, 29, 78, 9
to, 7
drilus
s, 86, 111
lus, 28,
influen
ae, 30,
iloides
rilus,
rilu
chaet
57, 61, 62, 83-86
lidae, 3
iculu
85, 90, 1
dril
chaet
r, earthw
na, 1
, earthworms
ilus,
ence in distri
11, 14, 87,
e wor
etina,
rili,
, 29, 61, 75, 76, 79,
, 19, 22, 80,
55, 62, 64, 80
80, 84, 87, 93
rodril
ilus,
olex,
aina,
e, 24, 48, 76
etus, 23
odri
drilu
, 83, 84, 94, 99, 102,
of earth
soni
ster, 57
9, 41, 57, 61, 81,
dae,
diu
is
lus, 18,
drilus,
nia, 76,
, 87, 95,
iella,
d, earthwo
worm
, 52, 72, 74, 76, 77, 83, 84, 86,
x, 80, 84
us, 7
e, 16, 32, 73
22, 73, 76, 78,
tinae, 1
16, 62, 80, 8
sium,
ands, earth
aeta, 23
hodri
llae
ais,
olex,
rilus,
a, worms
us, 42,
ryct
ne spec
rilus,
aetida
19, 22, 82
nyche
ex, 23,
sogas
80, 82, 84, 90, 94, 99, 102, 104, 105,
tothr
drili
us, 37, 3
riloid
tes (= H
a, 15, 55,
rilus,
ophle
ster, 19
87, 93, 95, 111,
tus, 25,
lus, 50,
72-74, 78, 79, 82, 83, 96, 97
iella,
tina
oryct
odril
drilus,
rilus,
drilu
lus, 86,
helmi
stes
ilus,
re, wor
a barri
rdael
of wo
lus, 24, 47
ella, 80
re (see
nia, 75,
aria
drilu
roa
ic arran
rilus,
scolex,
reutus,
todri
and distri
us (see Rh
anu
a, 8
chaeta
odril
er, 80,
, 15, 72, 80
ogen
ex, 3
ae, 33, 3
onu
enus
haet
vskye
icul
ia, 80,
14, 72,
teci
Y JOHN CLAY, M.A. AT
Romance
Werewolf
Romance
Romance
Billionaires
Romance