370 Proceedings oj the Royal Physical Society. 



worms, which proved on examination to belong to two 

 distinct species. One was a Luiyibricus, presenting no marked 

 differences from our British Lumhriciis terrestris ; and the 

 other a new species of the genus Acanthodrilus. 



As the Cape of Good Hope is a new locality for this genus, 

 I have thought it worth while to offer to the Society a few 

 notes upon the structure of the species which I propose to 

 name Acanthodrilus capensis. The pressure of other work has 

 prevented me from treating of its anatomy in a detailed 

 fashion, but the following notes will, I hope, be not without 

 value from a zoological point of view. 



The anatomy of earthworms has at present been but little 

 studied; but we are already acquainted with the fact that 

 these animals present a most remarkable diversity of internal 

 structure, coupled with a very general uniformity in external 

 characters; and it is sufficiently evident that there is an 

 absolute necessity for dissecting an earthworm in order to 

 define at all correctly the species or even the genus to which 

 it belongs. The necessity for accompanying purely descrip- 

 tive work with anatomical details is perhaps more obvious in 

 this group of the animal kingdom than in any other. The 

 published records of new species and genera of other groups — 

 for example, the Crustacea — which merely relate to external 

 form, are of the greatest possible use, from a zoological or 

 faunistic point of view. Of new species and genera of earth- 

 worms, such records are simply valueless, and any one who 

 has studied the anatomy of this group must be well aware of 

 the impossibility in many cases of verifying such descrip- 

 tions. The species which I shall describe in the present 

 paper clearly belongs to the genus Acanthodrilus of Perrier, 

 but it may also very possibly be referred to either of the two 

 genera — Alyattes or Eurydame of Kinberg. This naturalist 

 has defined his genera by the varying distribution of the 

 setae ; and the last-mentioned genera agree to differ from 

 the others of his system in that the set?e are arranged in 

 four series of pairs in the anterior region of the body, but in 

 eight longitudinal rows in the posterior section of the body, 

 the two setae of each pair becoming here separated from each 

 other. As a single instance of the impossibility of such a 



