}. DITKEMA. 245 



1. DITREMA*. 



Ditrema, Schleg. Faun. Japon. Poiss. p. 77. 



Embiotoca, Rhacochilus, Amphisticlius, et Holconotus, Af/assiz. 



llolcoiiotus, ^licroniotrus, Cymatogaster, Pachylabrus, M} tilophagus, 



et Ilj'jierprosopon, Gibbons. 

 Holconotus, Embiotoca, Damalichthys, Phanerodon, Abeona, Rhaco- 



chiliis, Amphistichus, et Ennichthys, Girurd. 



Body compressed, elevated, covered with cycloid scales of moderate 

 or rather small size ; mouth rather small ; teeth conical, in a single 

 series. One dorsal lin, the spinous portion of which is less developed 

 than the soft, and composed of seven to eleven spines ; anal with 

 three spines and numerous closely-set rays. Gills four, with a cleft 

 behind ; pseudobranchiiE well developed. 



West coast of North America ; one species from Japan. Entering 

 fresh waters. 



1. Ditrema jacksoni. 



Embiotoca iacksoni, Aqass. Am. Jmini. xvi. p. 387, xvii. p. 366, and 



Proc. Bod. Soc. Nat. Hist. 1861, p. 126 ; Girard, Proc. Acad. Nat. Sc. 



Phihtd. 1854, p. 151; 1855, p. 320, and U.S. Pacif. R. R. JExped.Fish. 



pi. 27, 28, 26. tigs. 3 & 4. 

 Holconotus fuliginosus, Gibbons, I*roc. Acad. Nat. Sc. Pkilad. 1854, 



p. 12.3. 

 Embiotoca cassidii, Girard, Proc. Acad. Nat. Sc. Philad. 1854, p. 151 ; 



1855, p. 320, and U.S. Padf. R. R. Exped. Fish. p. 171. pi. 29 & 26. 



fig. 12. 

 webbi, Girard, Proc. Acad. Nat. Sc. Philad. 1855, p. 320, and U.S. 



Pacif. R. R. Exped. Fish. p. 173. pi. 30. 



D. ^^. A. 2-g^. L. lat. 60. L. transv. 8/19. 



The middle and posterior dorsal spines are of nearly equal length, 

 shorter than the anterior rays. Scales on the cheek in four series. 

 The height of the body is one-half or somewhat less than one-half 

 of the total length (without caudal). Upper jaw a little longer than 

 the lower. The fold of the lower lip is interrupted in the middle. 

 The maxillaiy extends to, or nearly to, below the anterior margin of 

 the orbit. Caudal fin slightly forked. 



rt. Adult. San Francisco. Erom the Boston Museum. 

 6. Adult : not good state. San Francisco. Presented by the Smith- 

 sonian Institiition. 



2. Ditrema laterale. 



Embiotoca lateralis, Aqass. Am. Juuni. 1854, p. 366, and Proc. Host. 



Soc. Nat. Hist. 1861,"p. 126. 

 Ilolcniiotus n^assizii, (ribbons, IVoc. Acad. Nat. Sc. Phi/ad. 18.54,p.l21. 

 luubiotocalint-atn, Girard, Proc. Acad. Nat. Sc. Philad. 1854, pp. 134, 



141, 151 ; 1855, p. 320, and U.S Pacif. R. R. Exped. Fish. p. 174. 



pi. 31. 26. figs. 5 & 6. 



* 1. Embiotoca argjrosonia, Girard, Proc. Acad. Nat. Sc. Philad. 1856, p. 136, 

 and U.S. Pacif. R. R. E.rped. x. Fishes, p. 180. 

 2. Cymatogaster pidchcllus, Gibbons, Proc. Acad. Nat. Sc. Phdnd.\KA, p. 123. 

 — Holconotus pulclicllus, Ayass. Prvc. Host. Sue. Nat. Hist. 1861, p. 132. 



