488 WILLIAM NICOLL. 



Family AOANTHOCHASMIDAE. 



Genus ACANTHOCHASMUS Looss. 



Acanthochasmus imbutiformis (Molin). 



Looss, 1901, pp. 632-3 ; Johnstone, 1906, pp. 177-9. 



About thirty specimens of this parasite were found in the intestine of 



Lahrax lupus. 



What appears to be the larval stage of this parasite was found encysted 

 in the gills of the pipe-fish, Siphonostotna typhle. A single cyst containing 

 a Hving larva was also found on one occasion amongst the stomach 

 contents of a whiting {Gadus tnerlangus). 



The cysts in the gills of Siplioyiostoma are oval and measure •3--65 mm. 

 in length. The oral sucker is slightly larger than the ventral, and is 

 surrounded by eighteen cephalic spines. The cyst in the whiting had a 

 diameter of -38 mm. and the cercaria a length of 1-5 mm. The oral sucker 

 measured -15 mm. and the ventral -17 mm. The cephalic spines numbered 

 sighteen and measured -056 mm. in length. 



GASTEROSTOMATA. 



Of this sub-order eight different species were collected, only one of 

 which appears to be hitherto undescribed. A remarkable feature of this 

 group is the great variation in the anatomical topography which may 

 occur, even within specific limits. This variation affects chiefly the 

 position of the genital glands and of the mouth. The size of the excretory 

 vesicle also varies considerably. On the other hand, the position of the 

 yolk glands and the size of the cirrus-pouch are fairly constant. 



The variation is particularly well illustrated in the case of Proso- 

 rhynchus crucihulum (Rud.), in which as regards the position of the 

 genital glands no two descriptions have yet agreed. It has been pointed 

 out (Nicoll, 1910) that these discrepancies are due to the extreme varia- 

 tion in the position of the genital glands in this species. A similar, but 

 less extensive, variation is found in Prosorhynchus aculeatus Odhner. 



Within generic limits a still wider variation may be observed. In 

 illustration it is sufficient to compare the condition in Prosorhynchus 

 squmnatus Odhner with that in P. aculeatus. In the former the ovary and 

 testes lie almost directly one behind the other, along the right margin of 

 the middle part of the body. In P. aculeatus, on the other hand, they are 

 disposed in a triangle in the posterior part of the body, the ovary being 

 in front and the testes lying one ou each side of the body. 



