62. LEUCOSOMUS. 267 



The siK'cics may be arranged thus : — 



I. Caudal lobes equally developed. 



A. Pharyngeal teeth more or less compressed and tapering. 



1. Origin of the dorsal fin above, or in advance of, the root of the 



A-entrals, p. 267. 



2. Orig-in of the dorsal fin behind the root of the ventrals, p. 269. 



B. Son^e_of the pharyngeal teeth obtuse and molar-like {Myhcheilus), 



II. Upper caudal lobe more developed than the lower, p. 271. 



I. Caudal lobes eqiutUy developed. 



A. Pharyiujeal teeth more or less compressed and tapering. 



1. (hngin of the dorsal Jin above, or in advance of, the root of the ventral. 



1. Leucosomus synunetricus. 



rogonichthys symmetricus, Baird ^- Girard, Proc. Ac. Nat Sc 

 I'hilad. 18o4, p. 1.36; U. S. 4'- Pac. P. P. Kvp. Fish, p 246 

 The length of the head is one-fifth of the total (with the caudal) 

 1 ^'^t''^/lu u'^T^^f ^^"'° contained less than four times in the 

 ength of the head. Lower jaw shorter than the upper ; the maxil- 

 lary does not extend to the vertical from the front margin of the 

 eye Origin of the dorsal fin nearer to the root of the caudal than 

 to the end of the snout, and behind the origin of the ventrals. 

 Caudal lobes equaUy developed. Coloration uniform. (Girard ) 

 ban Joaqmm VaUey, CaHfomia. Length 4| inches. 



2. Leucosomus argyreiosus. 



Pogonichthys ^'gyjeio.us, Girard, Proc. Ac. Nat. Sc. Philad. 1854, 

 p. 1.54 ; and U. S. c^ Pac. P. P. Exped. Fish. p. 246. 

 D. 10. A. 10. V. 10. 

 The length of the head is one-fifth of the total (with the caudal) 

 Jiye large, its honzontal diameter being contained a Uttlo over three 

 times in the length of the head. Snout subconical, mouth subhori- 

 zontal : lower jaw shorter than the upper ; the maxillaiy reaches to 

 below the tront margin of the eye. The origin of the dorsal fin is 

 somewhat in advance of that of the ventrals, and equidistant from 

 the end of the snout and the root of the caudal. Lobes of caudal 

 fin equally developed. Pectorals rather small. (Girard ) 

 Presidio, California. Length 3| inches. 



3. Leucosomus communis. 



Pogonichthys communis Girard, Proc. Ac. Nat. Sc. Philad. 1856, 

 p. 188; and U. S ^- Pac. P. P. Fxp. Fish. p. 247, pi 55- Cove 

 Proc. Ac. Nat. Sc. Philad. 1864, p. 277. ^ ' ^' 



D. 10. A. 11. V. 9. 



Scales of moderate size. The height of the body is a Uttle less 



