PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 459 



tudiual ridges, which rise higher than the temporal ridges ; this entire 

 region nearly or quite destitute of scales [in T. exilis the middle of the 

 top of the cranium is scarcely elevated and without longitudinal ridges, 

 the whole region being more or less closely scaled] ; scales of frontal 

 region extending little forward of base of premaxillaries (in T. exilis, 

 extending for more than one-fourth the length of the premaxillaries.) 

 Cheeks well scaled ; scales on opercle very minute. 



Scales not very small, green. 



Dorsal tin beginning and ending behind anal, its origin above base 

 of fifth anal ray ; anterior rays of both fins produced ; median and pos- 

 terior rays equal, the latter not reaching nearly to base of caudal ; anal 

 lobe higher than dorsal lobe, its height four-fifths length of i)Ostorbital 

 part of head. Ventrals small, extending about one-third the distance 

 to origin of anal, their insertion midway between base of median caudal 

 rays and middle of cheeks. Pectorals broad, as long as postorbital part 

 of head, the upper ray broad. Caudal lunate, the lower lobe the longer; 

 the middle rays not quite twice as long as eye. 



Head 2^ in length; depth nearly 18. D. 1, IG; A. 1, 17; P. 13; Lat. 1. 

 ca. 250. 



Color ; greeu above ; white below ; a dusky dorsal stripe ; a silvery 

 lateral stripe; sides of head silvery; up])er part of cheeks punctulate; 

 body and tins without dark points ; a blackish half-bar between cheeks 

 and opercles ; a blackish blotch above eye and one in front of nostrils. 

 Fins olivaceous, all more or less dusky at tip. Posterior portion of pec- 

 torals abruptly black. 



This species is abundant at Mazatlan, where it is one of the common 

 market tishes. It reaches a length of about two feet, and it is known to 

 the Mexican fishermen as " Sicrrita.'''' 



It resembles its Californian representative, Tylosurus exilis, very 

 closely, differing in several details, some of Avhich are noticed above. 

 The two species may be distinguished at sight by the color of the pec- 

 torals, which are, in T. exilis, plain olivaceous. The dorsal and anal 

 lobes in the latter species are not dusky at tip. 



2. Tylosurus fodiator, sp. uov. (28190, 283-23.) 



A species of large size, remarkable for the great strength of its jaws. 



Body robust, subterete, as broad as deep ; caudal peduncle slightly 

 compressed, as deep or deeper than broad, the lateral line forming a 

 low black cutaneous fold along its length. 



Head very brosid and strong, the cheeks nearly vertical. Interorbital 

 space very broad, two-thirds length of postorbital part of head. Mid- 

 dle of top of head with a broad, shallow, nearly scaleless, longitudinal 

 groove; sides of top of head obliquely striated and rugose, forming a 

 prominent ridge above the eye; distance between nostrils greater than 

 usual, more than one-sixth length of snout. 



Jaws comparatively shortj tapering, very stiff and not fragile; lower 



