149-4 Bulletin 47, United States National Museum. 



Dr. William P. Gibbons in 1854, these fishes have been objects of special 

 interest to zoologists. Fishes of the Pacific coast of North America inhab- 

 iting bays and the surf on sandy beaches. Onespecies ( Hysterocarpus traski) 

 inhabits fresh waters; 3 others (JJitrema temmincM, Ditrcma smiitii, and 

 Neoditrema ransonneii) are found in Japan. These species reach a length of 

 from 6 to 18 inches, and are very abundant where found. They are much 

 used for food, but the flesh is comparatively poor, tasteless, and bony. 

 Most of them feed on crustacca, but 1 genus {Aheona) is partly or wholly 

 herbivorous. Genera 17 ; species about 20. 



HYSTEROCARPIN^ : 



I. Spinous dorsal longer than the soft part, of 16 to 18 spines; second anal spine the 



largest. Vertebraj 14 + 20 = 34. 



a. Scales large; teeih moderate, conical, in 1 series; lower lip without frennm; 



about 12 of the medium posterior teeth of pharyngeals large, all but the 



median 3 of these obliquely truncate molars, the rest small; gill rakers 



short, slender, 6 + 12. Hysterocarpus, 598. 



EMBIOTOCINiE : 



II. Spinous dorsal shorter than the soft part. 8 to 11 spines; anal spines graduated. 



h. Teeth incisor-like, most of them obtusely 3-lobed: lower lip with a narrow 

 frenum; outer series of pharyngeal teeth small, conic; the rest (about 32) 

 large molars closely appressed ; anal basis below 7 caudal vertebrie ; scales 

 large ; gill rakers long, slender, 6 + 14 ; sixth dorsal spine highest ; male 

 with a deep depression at the base of anterior anal rays ; a gland below 

 middle of the depression; vertebrte 14 + 20=34; herbivorous, feeding 

 largely on Viva. Abeona, 599. 



6&. Teeth entire, usually bluntly conic. 



c. Scales large, 36 to 50 in lateral line : soft dorsal and anal shortish ; size 

 small. 

 d. Lower lip thin, without frenum ; vertebrae 14 + 20 = 34; gill rakers 

 long, slender, 10 + 21 ; base of anal below 12 caudal vertebrae ; 

 central and posterior pharyngeal teeth blunt molars. 



Cymatogaster, 600. 

 dd. Lower lip thin, with a narrow frennm ; vertebra; 34. 



e. Head slender and pointed; gill rakers rather slender; body 



rather elongate, not greatly compressed ; dorsal rays VIIT, 



15. Brachyistids, 601. 



ee. Head rather deep and not pointed; gill rakers thickish ; body 



deep compressed; dorsal rays X, 18. Zalembius, 602. 



ce. Scales comparatively sm.all, 60 to 75 in lateral line. 



/. Teeth in each jaw in 2 series; male with 1 of the anterior rays of 

 the anal transformed into a triangular plate, the anal base form- 

 ing a decided angle at this point, the rays in front of it with a 

 thick covering of skin ; pharyngeal teeth mostly small, conic, 

 only a few in the last 2 series enlarged, some of these sometimes 

 truncate molars. 

 g. Lower lip without a frenum ; vertebra? 32 to 35. 



h. Gill rakers very long, slender and tapering, 23 to 29; anal 

 basis below 12 to 14 caudal vertebrae; body much com- 

 pressed. 

 i. Anal comparatively short, its rays III, 23. 



Hypocritichthys, 603. 

 U. Anal long, its rays III, 29 to 32; eye very large ; pro- 

 tile depressed above nape. Hyperprosopon, 604 

 hh. Gill rakers moderate, blunt and stout, 6 + 11; anal basis 

 below 11 caudal vertebrae; body less compressed. 



HOLCONOTUS, 605. 



