1886. ] LIITLE-KNOWN EARTHWORMS. 311 
Spermathece. | 2 pores.| d pores.| Clitellum. 
INOTDUGE™. «025... 8,9 14 18 14-17 
Wiis mbt ect 7,8 ee 16 12-15 
Set en ered ee 13, 14 18 
ee 8,9 15, 14 17 13-17 
ee SS ee el ayy aa. 15, 16 20 
» 9 (2) 8.9 14, 14 18 13-17 
oy OMS 4. ee 6,7 10 14, 15 
ORT: 7, 8, 9, 10 15, 16 18 
ELS il ae tGoAD Uf Waa ice sine 14, 15 18 
ome ante 7,8,9 14 17 
kOe rece 8, 9, 10, 11 15, 16 19 15-18 
vey AU eis 6, 7,8 13, 14 16 
» 12 (2) 8, 9 (right) ; 9, 10 (left) 14 18 
» 18(2) ..| 8,9 (right); 9,10 (left) | 14, 15 18 
fe eee eee 8,9 15,17 21 
fy me ware | ll aes Fee 15, 16 18 
In considering a series of variations like the present, it is necessary 
in the first place to discriminate between what are really variations 
and what are specific characters. I have stated at the commencement 
of this paper my belief that the anatomical differences between the 
individuals described here are variations, and not marks of specific 
difference. This opinion is based upon the following facts :—Firs¢, 
the exact correspondence in colour, size, and all anatomical charac- 
ters, except those liable to variation, between the different individuals. 
It may, perhaps, be objected that it is begging the question to 
assume that it is precisely those characters which are liable to 
variation in this “ species ” that are unimportant as marks of specific 
difference ; especially when it is remembered that these differences 
mainly concern the genital system, which is well known to exhibit 
constant and regular variation, serving as a basis of classification. It is 
indeed perfectly true that this isthe case ; but then the variations in 
the genital system are constantly accompanied by equally regular, 
though perhaps inconspicuous, variations in other characters ; so that 
a naturalist acquainted with this group could probably easily 
determine any species known to him by external characters only. It 
is not meant to iniply by this statement that external characters 
are sufficient to decide the systematic position of an Earthworm, but 
merely to emphasize the fact that when, after dissection, the relations 
of internal structure to external form are known, the latter charac- 
ters will serve as a guide to recognize the species. 
Secondly, the fact that the supposed variations are never represented 
by many specimens. Out of some 430 individuals I have recorded 15 
variations, 12 of which are exhibited in as many specimens, while 3 
are represented by two specimens apiece. The importance of 
this argument is in exact proportion to the number of specimens 
examined ; in the present instance it appears to me to be fairly 
sound. 
Thirdly, Earthworms are known to vary somewhat in structure, 
