58C CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



nature by Dr. Gibbous and Professor Agassi/, in 1853, these fishes have 

 been the subject of much interest to anatomists. 



Fishes of the Pacific coast of North America, inhabiting bays and 

 the surf on sandy beaches. One species (Hysterocarpus traslti) inhabits 

 fresh waters, one (" Ditrema" violaceum) is found in Australia, and 

 another (T)ltrcma temmincki) is found in Japan. The species reach a 

 length of from G to 18 inches, and are very abundant where found. 

 They are much used for food, but the flesh is poor and tasteless. Most 

 of them feed on Crustacea, but one genus (Abeona) is partly or wholly 

 herbivorous. Genera 8; species 20. 



(Embiotocidiii Giiuther, iv, 244-251.) 



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



largest. (Hystei-ocariiiiHr. ) 

 a. Scales large; teeth moderate, conical, in one series; lower lip without frenuni. 



HYSTEROCARPUS, 307. 

 ** Spinous dorsal shorter than the soft part, of S-ll spines; anal spines graduated. 



(Embiototince.) 



6. Scales large (40-50 in tha lateral liue); soft dorsal and anal more or less short- 

 ened. 



c. Teeth incisor-like, most of them obtusely three-lobed ; lower lip with a nar- 

 row freuum ABEOXA, 306. 



cc. Teeth conic, entire MiCKOMKTitrs, 309. 



bb. Scales small (00-75 in the lateral line). 



d. Teeth in two series in each jaw AMPIIISTICHI-S, 310. 



dd. Teeth in a single series in each jaw. 



e. Lower pharyngeal bone normal (with the posterior margin concave, the 

 the lateral horns well developed, and the teeth all on the same plane, 

 some conical, sonic truncate). 

 /. Lower lip with a frenuni, its edge entire. 



g. Abdomen much longer than the base of the short anal fin. 



HYPSURUS, 311. 

 gg. Abdomen much shorter than the base of the long anal tin. 



DITKKMA, 312. 

 ff. Lower lip without freuum, its free fold ineised behind; lips very 



large RuACOCim.rs, 313. 



ee. Lower pharyngeals peculiar, very large, posteriorly convex, the lateral 

 horns little developed, the teeth on two separate planes which meet 

 at an angle, the anterior teeth hexagonal and tessellated, the posterior 

 appressed forwards DAMALICHTIIYS, 314. 



3O7. HYSTEKOCARPUS Gibbons. 



(KihhoiiH, Daily I'laeer Times and Transcript, May 18, 1854, and in Proc. Acail. Nat. 

 Sci. I'hila. Ktl, l'J4: type //i/.s/rnxvir/M/* trnxki Gibbons.) 



Body ovatr, tin- back strongly ele\ ated and convex; head small, the 

 snout projreting; month small, with one scries of rather large, bluntly 

 conical teeth ; the jaws about ecpial ; lips not much enlarged, the lower 

 forming a free border, without frennm; gill rakers moderate, widely set; 

 branchiostegals ."> ; scales rather large, silvery; spinous dorsal very 



