312 MR. F. E. BEDDARD ON NEW OR [May 18, 
though there has never, to my knowledge, been described so great a 
number of variations as I have been able to record in the present 
communication. Dr. Horst’ has recorded a variation in the form 
of the spermathecee of Pericheta indica and in the ceca of 
Pericheta musica, and Perrier* in the spermatheex of Pericheta 
affinis. 
Fourthly, and lastly, the probability, suggested above, of the 
occurrence of variations must not be left out of sight. 
Assuming it to be proved that an actual variation does occur in 
the present species, it will be necessary in the next place to eliminate 
those variations that are mere monstrosities, and that can hardly be 
considered to have any importance. Such are the occasional doubling 
of segments on one side of the body, as the variations Nos. 4, 12, and 
14; these are comparable to such monstrosities among Vertebrata 
as two-headed lambs, calves with five limbs, and so forth, which are 
not in any sense reversions to an ancestral type, but are owing to 
some accidental cause, such as defective or excessive nutrition. On 
the other hand, the remaining variations are to my mind of some 
importance. These will now be considered in some detail. 
It must be noted first of all that the variations occur in the 
generative system, and it is precisely the modifications of this system 
which have enabled systematists to classify the group. 
These variations affect all the parts of the generative system—the 
clitellum, the ovaries and their ducts, the spermathecze, and the male 
organs. 
I will commence with the clitellum. This organ and the relations 
which it bears to the male generative apertures has enabled M. 
Perrier to classify the whole group, after a fashion which is in the 
main satisfactory, though open to objections in certain cases. I have 
elsewhere urged that, in so far as it separates the Anticlitellians, 7. e. 
Ivmbricus and its allies, from the remaining genera of Earthworms, 
M. Perrier’s system is by no means artificial, but bears out other 
anatomical differences. To distinguish the Intra- and Postclitellians 
from each other is not so easy a task: in the first place, we have genera 
like Megascolex, whose affinities are clearly with Pericheta, and which 
yet possess Intraclitellian generative apertures ; in the second place, 
we find that within the limits of a single genus, i. e. Acanthodrilus, 
the male generative orifices vary in position, and may be either intra- 
or post-clitellian. 
If the relations of the clitellum to the male generative apertures be 
used for classificatory purposes, it appears to me necessary somewhat 
to alter Perrier’s definition, and to divide Earthworins into two 
groups, according as to whether the clitellum is placed far forward, 
and commences in front of the male generative orifices, or whether 
it is placed further back and commences behind the male generative 
orifices. 
That there is really a connection between the clitellum and the 
1 Notes from the Leyden Museum, vol. v. p. 182. 
? Nouvelles Arch. &e. loc. cit. p. 106. These facts are of course liable to the 
same criticism as my own. 
