1494 Bulletin //, United States National Museum. 



J 



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. One species (Hysterocarpus trasJci) 

 inhabits fresh waters; 3 others (Ditrema temmincki, Ditrema smittii, and 

 Neoditrema ramonneli} 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 Crustacea, but 1 genus (Abeona) is partly or wholly 

 herbivorous. Genera 17 ; species about 20. 



HYSTEROCARPIKLE : 



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



largest. Vertebrae 14 + 20 = 34. 



a. Scales large; teeth moderate, conical, in 1 series; lower lip without frenum; 

 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. 



EMBIOTOCHO5 : 



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



b. 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 vertebrae ; 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; vertebrae 14 + 20=34; herbivorous, feeding 

 largely on TTlva. ABEONA, 599. 



bb. 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 frenum ; vertebrae 34. 



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



rather elongate, not greatly compressed ; dorsal rays VIII, 



15. BRACHYISTIUS, 601. 



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



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



cc. Scales comparatively small, 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 ; vertebrae 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. 



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

 file depressed above nape. HYPERPROSOPON, 604 

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

 below 11 caudal vertebras; body less compressed. 



HOLCONOTUS, 605. 



