156 Transactions, — Zoology. 



and has recently received from him the varietal name " cur- 

 ticaudatus." In fully mature specimens of Acanthodrihis roses 

 the average number of post-clitellian segments is about 226. 

 I have, however, met with two individuals, one having only 

 37, the other 49. In such individuals the posterior extremity 

 of the body is not attenuated a.s in normal specimens ; it is of 

 the natural size of the body where it abruptly terminates, and 

 is almost flat. Similar specimens of Acanthodrilus novcB-zea- 

 landue and OctocJiatus thomasl also occur. The segments 

 composing the flat posterior extremity narrow within each other 

 in a series of rings towards the anus. These deformities are 

 also common in Luvihricus yurpureus, Eisen, another intro- 

 duced species. I possess specimens of the latter species and 

 L. ruhcllus, with the clitellum, as the Kev. Mr. Friend observes, 

 " right in the middle of the body." At the present time it is 

 important to call the attention of zoologists to these matters, 

 seeing that they occur in widely-separated and widely-distri- 

 buted genera. The careful study of such abnormal forms 

 would, unquestionably, yield interesting and valuable results, 

 morph ologically . 



Excepting some remarks by the Eev. Mr. Friend on abnor- 

 malities in two species of British earthworms, little attention 

 has hitherto been given by naturalists to their great variability. 

 Eisen has also shown that the clitellum in some species of 

 European Lumbricus is occasionally moved one or more seg- 

 ments back or forward on the body of the worm. Both these 

 peculiarities in structure occur occasionally in both introduced 

 and native worms. Eeferring to LumbrlcKS ruhcllus, var. 

 curticaudatus,''- the Eev. Mr. Friend says, " I have failed so 

 far to determine whether the efl'ect is due to soil, height above 

 sea-level, want of proper food, or otherwise." I cannot clearly 

 conceive how any of these causes could produce a structurally 

 imperfect worm. I think it is more probably due to some de- 

 fect in the embryonic development of the worm, and not to the 

 effect of any cause after its emergence from the cocoon. 

 Animals belonging to both lower and higher groups than earth- 

 worms are occasionally born without certain limbs, or other 

 parts of their bodies, the result of causes of which little is 

 known at present. The var. curtictmdatus, Friend, occurs 

 among many thousands of the species living together in the 

 rubbish-heaps on the banks of the Ashburton Eiver. The 

 heaps consist of rotten straw, old bags, paper, tins, etc., thrown 

 out from the shops. When rotten the worms collect into and 

 breed in them in vast numbers. The largest and finest 

 developed specimens of several exotic species are generally 

 obtainable in similar heaps wherever they accumulate. 



* Loc. cit. 



