SEA-FISHERIES LABORATORY. 291 



hook, very large, is bent sharply round, about as far as an 

 ordinary fish hook. Some of these large hooks have spurs 

 on their proximal extremities. The other hooks are small, 

 almost straight, and with slightly expanded bases. The 

 contractile bnlbs are long and narrow. 



The larva bears a very strong resemblance to 

 Rhynchcibothrium irrvparis'pinc, Linton*, a form described 

 from Raia erinacea. But the latter worm is probably 

 identical with, or is a variety of Tetrarhynehus erinaceus, 

 van Beneden, a form described in the adult stage from 

 Rain species, and as a larva from Gadoids and Trigla. 



ACAXTHOCEPHALA. 



Echinorhynchus acus, Rudolphi. 



A small haddock, about 9 inches long, dissected 

 during the fishermen's classes of 1904, yielded about 50 

 specimens of this acanthocephalan. The parasites were 

 attached to the wall of the intestine immediately behind 

 the pylorus. I am identifying them as E. acus, though 

 they differ in some respects from the worm usually 

 described as this form. They were of two lengths. The 

 smaller were about 12mm. in length, and the largest about 

 30-35nini. There were few intermediate sizes. The 

 proboscis was about 1mm. in length. The worms were 

 lightly attached to the intestinal wall, and were easily 

 detached. On killing in fresh water the proboscis was 

 invariably protruded, and was nearly always slightly bent 

 from the longitudinal axis of the body. Text-fig. 8 

 represents the tip of the proboscis. There are 12 to 13 

 longitudinal rows of hooks, which are not arranged trans- 

 versely, but spirally, and each spiral contains 15 to 1G 



* Report U. S. A. Coram. Fish and Fisheries for 1887, 1891. p. 841, 

 pi. xii., figs. 8 and 9. 



