NO. 2125. FISHES FROM THE GULF OF CALIFOR^^IASNYDER. 579 



One is justified in looking forward to the possible discovery of one 

 or even more undescribed forms, or at least to the extension of the 

 range, of known species. It is quite within reason to presume that 

 N. generosus is represented in the upper Columbia Basin. The 

 status of platyrhynchus, jordani, and columhianus should be carefuUy 

 investigated. 



The specimens here used for comparison were about 6 inches long, 

 perhaps the average size of mature individuals. In very old exam- 

 ples of Pantosteus the fontaneUe becomes linear. In the large type 

 of P. inrescens the parietaLs and frontals nearly meet. 



The smallest specimen of N. clarki examined measured 70 mm. in 

 length. No fontaneUe was present, but the parietals and frontals 

 were not very firmly united along the median line. 



Beaver Creek, Santa Cruz River. 



XYRAUCHEN TEXANUS Abbott-i 



This species is remarkable for the high and narrow dorsal hump or 

 keel which rises abruptly from the rather low, flat head, and extends 

 to the dorsal fin. The bony structure of this keel is formed by the 

 junction of an enlarged occipital crest and a series of fused or closely 

 apposed and modified spines and intern eurals. The anterior and 

 stronger part of the crest is supported by the complex of vertebrae 

 over which the chain of Weberian ossicles extends (fig. 6). This 

 complex involves 3 developed vertebrae, no trace of another ap- 

 pearing in the mature skeleton. The first of these is represented 

 by a thin centrum without lateral processes, above which is the 

 spine {S.l), narrow and knife-like, with a heavy, thick base, closely 

 apposed to the first interneural {%.!.), the base of the second verte- 

 bral spine and the neural arch. The second vertebra is not anky- 

 losed with either the first or third. Its neural arch is large, and the 

 spine (iS. 2) above it is massive. With the second spine are firmly 

 coosified the broad, leaf-like interneurals between the first and fifth 

 spines. This spine-interneural complex is the "trapezoidal inter- 

 neural" of Lockington 2 and the ''large, interneural formed by a 

 thick central pdlar with anterior and posterior wings'' of Kirsch.^ 

 The third spine {S. 3) is broad and low, closely joined to the base of 

 the second, or ankylosed with it. The fourth is slender, short, and 

 supplied with a bifid tip which clasps the lower edges of the last 

 fused interneurals. Five other interneurals (one of which is occa- 

 sionally absent or partly developed) with thin, broad tips and narrow, 

 pointed bases, together with the first interneural of the dorsal fin 

 finally complete the bony crest. 



1 Fowler finds that X. cypho of authors is C. texantu Abbott. Proc. Acad. Nat. Sci. Phila., 1913, p. 54. 



* Proc. Acad. Nat. Sci. Phfla., 18S0, p. 237. 



* Proc. U.S.Nat.Mus., vol. 11, 1888, p. 556, description of Xt/rauthen Eigenmann and Earsch, new genus. 



