cJose to the Atlantic H. americanus (Gmelin) and "perhaps not distinct from the 

 proceeding". P. Y. Schmidt (1904) synonymized the two forms; Soldatov and 

 Lindberg (1930) following Jordan & Snyder considered as a separate form H. 

 villosus (Pallas) from the Pacific Ocean . However, the majority of writers 

 comparing species with the Atlantic type did not have both forms at once . In the 

 ichthyological laboratory of the Leningrad University is an example of Hemitrip - 

 terus americanus (from the Smithsonian Institution) from the east coast of 

 North America (coll. 1877, no. 297a) which I compared with examples from the 

 Japan Sea (coll . K . M . Derjugin) and also Avachin Bay (coll . K . A . Vinogradova) . 

 After comparing examples of the same size, the following differences were noted: 



North Pacific Ocean—' 



1/ 



North Atlantic Ocean-' 



2/ 



1. ID (XVI) XVII-XVIIl 



1. ID XVI 



2 . Interorbital and occipital 

 region concave. 



2 . Interorbital slightly concave, occiput 

 flat. 



Occipital tubercles low dis- 

 tance between anterior and 

 posterior pair is less than 

 1/3 interorbital (27-32% of 

 interorbital) . 



3 . Occipital tubercles higher, distance 



between pairs is more than 1/2 interorbital 

 (58% of interorbital). 



4 . Interorbital in head (to end 

 of opercular) 36.2-37.6%. 



4 . Interorbital 28 . 7% of head . 



5 . Many tubes of LL have inte- 

 gumentary flaps . 



5. No. flaps. 



6 . Cheeks covered with high coni- 

 cal cirri . 



6 . Cheek cirri sparce and low . 



7 . Behind postorbital tubercle a 

 small comb-cirris. 



7. One pair of low tubercles between 

 eyes and nape . 



8. Large conical papillae cover- 8. Body papillae small, head flaps 



ing body and abdomen below weakly developed, 



lateral line . Flaps on head 

 well developed. 



9. Pectoral length 23.5-24.5% SL. 9. Pectoral fin 31, 9% SL. 



i/ 

 2/ 



Material for comparison: 1 ex from Japan Sea (270 mm); 1 ex Avachin Bay (390 mm). 



From ex 297 a from Smith. Inst, from Eastern NA (320 mm). 



31 



