MUSEUM OF COMPARATIVE ZOOLOGY. 169 



Total length 19.0 inches. 



Snout to end of ventrals 10.2 " 



Snout to vent 8.0 " 



Snout to mouth 3.5 " 



Width of pectorals 6.9 " 



Twenty-one specimens from Payta, Callao, and Galapagos Islands, collected 



by the Hassler Expedition. 



Trigonorhina alveata n. sp. 



Disk, including the ventrals, rhombic, longer than wide. Anterior borders 

 of pectorals nearly straight ; posterior convex. Snout truncated, as wide on 

 the end as the space between the eyes. Rostral cartilage wide and strong, 

 deeply grooved on its upper surface. Rostral ridges prominent, widely sepa- 

 rated, nearly or quite parallel from base to extremity. Spiracles large, equal 

 in diameter to the orbit, without a fold on the side. Fin angles rounded, with, 

 the exception of the obtuse posterior angles of the dorsals. Dorsals elevated, 

 behind the ventrals ; the length of the base of the first less than the length of 

 its posterior border ; base of the second equal to its posterior margin. The 

 base of the first is equal to its distance from the ventral or the second dorsal. 

 Anterior nasal valves dilated, continued beyond the inner angles of the nostrils, 

 but separated from each other by an interspace ; posterior two-lobed. Anterior 

 extremities of the pectorals widely separated from the rostral cartilage, extend- 

 ing very little in advance of the eyes. Mouth in a low arch, regularly curved 

 from the corners. Teeth small, blunt, in a hundred and ten series in the upper 

 jaw. Claspers long, slender, knobbed at the end. Tail with a thick fold on 

 each side. Caudal fin rounded, without indentation. Back thickly covered 

 with small scales, among which are scattered larger ones. A median row of 

 large blunt tubercles on back and tail, and two short rows parallel to this on 

 each shoulder. The bases of the tubercles are so covered by the skin and small 

 scales that they appear as rounded prominences with a small spine on the 

 summit. 



Color grayish brown. Near the extremities of the rostral ridges there is a 

 band of dark brown ; between this and another dark band which crosses the 

 bases of the ridges there is a light band. A dark band across the head between 

 the eyes is somewhat confluent with the band in front of it, which makes the 

 fore part of the head dark, but leaves the prominences in front of the eyes light- 

 colored. The remainder of the upper surface is more or less clouded by faint 

 indications of transverse bands. These are probably distinct in the young. 

 With the exception of a dark spot on the posterior angle of each pectoral, tho 

 lower surface is white. 



Total length 33.4 inches. 



Snout to end of ventrals 18.0 " 



Width of pectorals 15.5 " 



Snout to vent 13.3 <' 



Snout to mouth 4.1 " 



Width of mouth 2.5 " 



Distance between outer ancjles of nostrils . . 3.2 " 



