438 LARVAL TREMATODES OF THE NORTHUMBERLAND COAST. 



To show how many there are to be found I give here a list 

 of Mollusca, with the number of species of Trematodes infest- 

 ing them. Up to the present I have noted i8 species of 

 Trematodes, some of which occur in more than one kind of 

 mollusk. Probably many more will be discovered hereafter, 

 for besides those inhabiting Mollusca, many encysted cercariae 

 occurred in Crustacea ; for instance in the common barnacle 

 Balamis balanoides, the green crab Carcinus vicenas, and 

 Cerophhun grossipes, details of which will, I hope, be given 

 in a later paper. 



Mollusca infested by Trematodes. 



5 species of Trematodes. 

 3 



Cardium ediile ... 

 Mytilus ednlis ... 

 Macotna balthica 

 My a arenaria ... 

 Scrobiailaria tenuis 

 Tellina tenuis ... 

 Donax %Httatus ... 

 Littorina littorea 

 L. rudis ... 

 L. obtusata 

 PurpU7-a lapillus 

 Buccinum undatum 

 Paludestrina stagnalis 



This list includes most of the commoner Mollusca of this 

 coast. 



The liver is the most usual place for sporocysts and redife 

 (as in Littorina littoj-ea, L. rudis, etc.*), but often the repro- 

 ductive organs are infested (as in Cardium edule]), or the 

 kidney (as in Littorina littoreaW or it may infest the whole 

 animal (as Bucephalus hainieanus in tlie cockle§). Encysted 

 cercariae may occur in any part, but frequently seem to prefer 

 the foot {Ec/iinostomum leptosoinum in Scrohicularia tenuis and 



* Noi-thumberland Fisheries Report for 1905. 



t Annals and Maj,'. Nat. Hist., Jan., 1907. 



X Lesp^s, Annales des Sciences Naturelles, S^r. IV., Tom 7, 1857. 



§ Lacaze-Dutliiers, Ann. des Sci. Nat., S(5r. IV., Tom 1, 1854. 



