ADDITIONAL L.M.B.C. TURBELLABJA. 171 



in the brain, &c. From G. tethydicola it is at once dis- 

 tinguishable by the possession of eyes, and absence of the 

 very striking epidermal glands. G. braunii also possesses 

 the " Haftapparat," while the "excretory" tubules are 

 very distinctive, the testes are in front of the atrium, the 

 germ glands also present quite different relations. With 

 regard to G. mytili, as since Levinsen (10) published his 

 original description no specimens have been found, its 

 position is doubtful, but Levinsen's description supplies 

 quite enough details to prove that it is distinct from the 

 worm I am describing. " Ovaria longa, sacciforma intra 

 margines laterales sita " is sufficient in itself to distinguish 

 G. mytili from G. buccinicola, to say nothing of the further 

 statement in the Danish text, where he describes it as 

 extending itself along the side of the body from the eyes 

 far backwards, as a pair of broad sinuous sacks. His 

 sketch and description of the seminal vesicle and penis 

 have also no resemblance to the same structures in my 

 species. 



Habitat : — In the kidney and renal duct of Buccinum 

 undatum and Fusus antiquus. The greater number of 

 specimens of both these molluscs were infected, the 

 number of parasites in one host varied between four and 

 several dozen. A few worms were generally present in 

 the mantle cavity as well, into which they had probably 

 escaped through the renal aperture. The movements of 

 this species are sluggish, like the other members of the 

 genus it frequently lies on its side with the body dorso- 

 ventrally flexed and swims round in a circle. From my 

 observations upon living examples, kept in sea-water, I 

 find that it is extremely sensitive to light, hiding under 

 any object that is put into the vessel with it. 



As the specimens of Buccinum which I examined were 

 procured from the fishermen (who use them as bait), and 



