30 Fishery Board for Scotland. 



Worm Parasites of Fishes. 



Trichina sp. — A trichina-like parasite, resembling that which 

 occurs in the muscles of the Cod,* was observed in the muscle of 

 Sehastes marinus. I have found the muscles of Conyer vulyaris also 

 infected with Trichina. 



An experiment to test the resistance of the Trichina in a fish 

 fillet was made by Mr. Erlandson. The fillet was subjected to 

 strong salt solution and to smoking for double the usual time. 

 Thereafter two live worms and two dead worms were extracted. Nine 

 days later a number of worms were taken out, but all were apparently 

 dead. 



Tetrarhynchus megacephalus (Kud.). — A young stage of this 

 worm occurs frequently in Saithe caught near Iceland. It is shown 

 in natural size, after preservation, in fig. 133. Thirteent examples 

 have been found in one fish. They were located between the peri- 

 toneum and the wall of the abdomen. One was found inside the 

 swim-bladder. I have observed this form inside the mesentery. 

 Lonnberg describes under the name Tetrarhynchus linguatula (P. v. 

 Beneden) the same young parasite. It was attached to the ventrical 

 wall of the abdomen of a saithe. It measured 27 mm. in length, and 

 6 mm. in width. A similar form has been recently described by 

 Johnstone under the name Ccenomorphus linguatula (Van Beneden). 

 The specimens were adhering to the liver of a Saithe captured near 

 St. Kilda. The author states that Tetrarhynchus megacephalus 

 (Pud.) may be the final form of Ccenomorphus. 



Van Beneden described a large example of this species which he 

 had found in the gut of a Greenland Shark (Scimnus ylacialis). 

 Dr. T. Scott, who kindly drew my attention to Van Beneden's paper, 

 has recorded an example 18 inches long from the intestine of the 

 same fish. 



Tetrarhynchus erinaceus (Van Beneden).— Cysts of this worm 

 were found in the muscles of a Sebastes marinus. They were brown 

 coloured. The contained larva was white. The ruptured cyst 

 shown in A., fig. 37, measured 13 cm. in length. The pear-shaped 

 larva (A. and B.) was about 5 mm. in length and 2*5 mm. in 

 greatest width. Other cysts measured '35 by '1 mm. and "2 by 

 about 05 mm. 



Several of the larvse extracted from the cysts were put into fresh 

 water. They became active at once, and began to extend their 

 bodies. One eventually everted at the broad extremity a long 

 process bearing four toothed horns (fig. 37c). A sketch of some of 

 the hooks that adorned the horn is given in fig. ib. D. Another larva 

 everted from the posterior end a comb-like process. 



This is evidently the young form of Tetrarhynchus erinaceus (Van 

 Beneden). Scott found the species in small cysts in the walls of the 

 stomach and pyloric casca of cod and saithe. Johnstone has recently 

 given a detailed description of the adult and larva. 



Tlchinorhynchus acus (Rud.). — A specimen of this species (fig. 134) 

 was sent to the Laboratory attached to the peritoneum of a fish. 

 The latter was probably a saithe. Scott found the parasite in the 

 intestine of the saithe. 



* Williamson : "Eggs of Angler, etc." t Presented by Mr. H. Cardno. 



