1900.] STEW SPECIES OF EARTHWORM. 655 



have been examined microscopically ; our knowledge of the more 

 minute structure of the genus is indeed limited to that of the 

 smaller forms. I have investigated the structure of the body-wall 

 in the present species, which shows certain features worthy of note. 

 The first point to which I direct attention is the vascularity of 

 the epidermis. This structual peculiarity occurs, but is not common, 

 among earthworms. I was myself the first to announce that 

 certain Oligochteta resemble the Leeches (in which group the fact 

 had been previously ascertained by Lankester) in having a vas- 

 cular epidermis. 1 This character, however, has not been found in 

 many earthworms. It seems to me therefore to be worth recording 

 the fact that the Benhamia which forms the subject of the present 

 communication has a vascular epidermis. It appeared to me more- 

 over to be more abundantly vascular than I have observed to be the 

 case elsewhere. The capillaries are very readily seen owing to 

 their being injected with their own blood ; they penetrate the 

 actual epidermis as loops which reach perhaps halfway through the 

 thickness of the epidermic layer. I could find no trace of their 

 opening on to the exterior, which has been asserted by the Messrs. 

 Sarasin in the case of Perichceta. 



It is also to be noted that in the anterior region of the body, 

 at any rate in the neighbourhood of the spermathecae, intra-epi- 

 dermic capillaries are so rare as to be practically absent. I only 

 saw one or two loops in a large number of sections. They can be 

 of but little functional importance in this part of the body ; but 

 they are clearly of great functional importance towards the hinder 

 end of the body. As a matter of fact these capillaries do not 

 apparently penetrate the epidermis at the very end of the body ; 

 but this may conceivably be due to fresh growth in this region. 

 That the epidermis should be especially vascular posteriorly is 

 interesting when we reflect that it is in this situation that gills are 

 chiefly developed in branchiate Oligochseta. 



A second point of interest concerning the body-wall of this 

 species is that the longitudinal muscles have the bipinnate arrange- 

 ment, first described by Claparede in Lumbricus, but not by any 

 means universal among earthworms. 



Internal Structure. 



The accompanying drawing (fig. 2, p. 656) illustrates a general 

 view of the internal viscera, and expresses at the same time some of 

 the specific peculiarities of the species. The anterior portion of the 

 two gizzards (which completely hide the underlying spermathecse) 

 is to be noticed. The position of the calciferous glands (ca), the 

 last pair of which are situated in the xvith segment, is important ; 

 and also the fact that the large intestine may be said to com- 

 mence in the xxist segment, as it does not attain to its greatest 



T " On the Anatomy and Histology of Pleurocfaeta moseleyi," Trans. Eoy. Soc. 

 Edinb. 1880, and " On the Structure of the Body-wall in certain Earth- 

 worms," Proc. Eoy. Phys. Soc. Edinb. 1881. 



43* 



