290 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Tetrarhynchus erinaceus, van Beneden. 

 (From the Gurnard.) 

 About a dozen cysts containing larval Tetrarhynchi 

 were found by Mr. H. C. Chadwick in the body cavity of 

 a specimen of Trigla kirundo, dissected by him at the 

 Port Erin Biological Station. The cysts were pear- 

 shaped, and about 5mm. long, and of variable breadth. 

 The broader ends were pearly-white in colour, and the 

 narrower ends slightly yellowish. On dissecting these 

 cysts each was seen to contain a Tetrarhynchid lying 

 coiled up in the broader end. One contained also a 

 trematode worm, but this latter was certainly an intruder. 

 The tetrarhynchid is coiled up in a double S-shaped twist 

 SS. If the two adjacent extremities of the letters are 



Fig. 7. A group of hooks from a proboscis of Tetrarhynchus 

 erinaceus. x 1500 dia. 



joined, and the paper is then folded, so that the letters lie 



side by side, the coils of the worm are represented. The 



worm, when straightened out, is about 4 to 5mm. in 



length. It is unsegmented, and possesses two moderately 



long bothria. The hooks of the proboscides are the most 



extraordinary features in the organisation of the animal. 



There are at least two different forms of these structures. 



Their appearance in the proboscis, when the latter is 



retracted, is shown in Text-fig. 7, and several isolated 



hooks ore represented in the same figure. One kind of 



