94 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



The dorsal spines are slender, exiguous, and smooth upon their edges ; the anterior one is 

 inserted immediately above the base of the pectorals, and when bent horizontally backwards, it 

 does not quite reach the base of the second. The same is true of the second with reference to 

 the third. The origin of the second dorsal is a little nearer to the extremity of the caudal than 

 the tip of the snout ; it is also placed somewhat posteriorly to a vertical line reached by the tips 

 of the ossa innominata. The fin itself is composed of eleven articulated rays, the central ones 

 being slightly bifurcated. The caudal, which enters six times and a half in the total length, is 

 posteriorly sub-crescentio ; it is composed of the usual number of rays. The origin of the anal 

 fin is opposite the fifth or sixth ray of the second dorsal ; it is composed of seven articulated 

 rays, the central ones being but very slightly bifurcated. The anal spine is inconspicuous and 

 somewhat smaller than the third dorsal at the anterior margin of the soft fin. The ventral 

 spine is of moderate development, serrated upon both edges, more conspicuously above and near 

 its base than below. Its origin or insertion is a little in advance of the second dorsal spine, 

 and its extremity does not extend as far as the tips of the ossa innominata. The pectoral fins 

 are well developed, broadly sub-truncated upon their periphery, and composed of ten undivided 

 rays. The ossa innominata constitutes beneath a rather small spear-shaped shield, the ex 

 tremity of which does not reach the vent ; the vertical process is narrow and slender. The 

 cubital expansion is well developed. 



D I, T, I, 11 ; A I, 7 ; C 3, 1, 5, 5, 1, 2 ; V I, 1 ; P 10. 



The surface of the body is perfectly smooth ; in that respect G. ivilliamsoni may at once be 

 distinguished from the foregoing species, which are either entirely or partially protected with 

 bony shields. The lateral line follows the middle of the flanks from the origin of the second 

 dorsal fin posteriorly ; anteriorly it is somewhat nearer the back than the belly. 



The ground color is olivaceous brown, darker on the dorsal region than along the sides, which 

 are spotted with black ; beneath, of a soiled yellow. 



Specimens of this species were collected at Williamson s Pass, California. The waters from 

 this place reach the Pacific during the rainy season. In the dry season the waters remain in 

 isolated pools. 



List of specimens. 



