62. LE0COSOMUS. 207 



The species may be arranged thus: — 



I. Cauual lobes equally developed. 



A. Pliaryngeal teeth more or less compressed and tapering. 



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



ventrals, p. 207. 



2. Origin of the dorsal fin behind the root of the Aentrals, p. 2G9. 



B. Some of the pharyngeal teeth obtuse and molar-like {Mylocheilus)j 



p. 270. 



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



I. Caudal Iches equally devvk>j)ed. 



A. Phai'ynyeal teeth more or less compressed and taperiny. 



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



1. Leucosomus symmetricus. 



Pogonichthys symmetricus, Baird 8f Girard, Proc. Ac. Nat. Sc. 

 Philad. 1854, p. 136; U. S. S^- Pac. R. R. Exp. Fish. p. 240. 



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

 Eye large, its diameter being contained less than four times in the 

 length 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 equally developed. Coloration uniform. {Oifard.) 



San Joaquim Valley, California, Length 4^ inches, 



2, Lencosomus argyreiosus. 



Pogonichthys argyreiosus, Girard, Proc. Ac. Nat. Sc. Philad. 1854, 

 p. 154 ; and U. S. 8f Pac. R. R. Exped. Fish. p. 240. 



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



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

 Eye large, its hoiizontal diameter being contained a little 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 front 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. 185G, 

 p. 188 ; and U. S. i^ Pac. R. R. Exp. Fish. p. 247, pi. 55 : Cope, 

 Proc. Ac. Nat. Sc. Philad 1804, p. 277. 



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



Scales of moderate size. The height of the body is a little les^ 



