242 



Dr. W. NIcoll and Mr. W. Small on 



the oral having a diameter of '120 mm. and the ventral 

 •152 mm. ; the latter is situated at the beginning of the 

 posterior third of the body. The cuticle is smooth and 

 without spines. Just behind the ventral sucker two small 

 oval testes are placed, one on each side, with their long axes 

 directed obliquely outwards and forwards. The ovary could 



liiT. 1. 



Vei carta limcB. 



not be distinguished, being ])robably concealed by the ventral 

 sucker. A short excretory vesicle lies at the posterior end of 

 the body. There is a small pharynx contiguous with the 

 oial sucker; two simple intestinal diverticula arise im- 

 mediately behind the pharynx and appear to terminate near 

 the testes. 



This is apparently the first record of this cercaria, and 

 no other entozoa have hitherto been described from Lima 

 Mans. 



Even with the scanty details given above, it is not difficult 

 to recognize in this cercaria the larva of a species belonging 

 to one or other of the genera Steringophoriis or Fetlodistomum. 

 The position of the suckers, their large size and particularly 

 the prominence of the ventral sucker, the situation of the 

 testes, and the smooth condition of the cuticle all support 

 such an identification. The characters of the excretory 

 vesicle and the alimentary system are also of importance. 

 Moreover, these are the only two genera of British Trematodes 

 with which the cercaria shows any affinity. More detailed 

 differentiation seems at present out of the question. The 

 small excretory vesicle without conspicuous lateral stems and 



