PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 31 



Tube of the anterior nostril half as long as the eye; the posterior 

 nostril with a slight membranous expansion, not forming a tube; diam- 

 eter of eye contained 2 J times in the length of the snout, being placed 

 nearly above the middle of the gape; gill oiiening slightly longer than 

 the eye. 



Sides of the upper jaw with two seiies of teeth posteriorly ; the outer 

 series small, close-set, somewhat triangular in form, slightly recurved, 

 immovable; the inner series similar in form, but much larger, depressi- 

 ble, the series not extending so far back as the outer and consisting of 

 about five teeth; the two series separated by a well-defined groove; in 

 front of these, and continuous with the outer series, are three nearly 

 fixed knife-shaped teeth, the posterior the larger, next a movable tooth 

 similar to the last fixed one but smaller, and three small fixed teeth in 

 front. On the middle line of the vomer are three depressible, fang-like, 

 arrow-shaped teeth, the first rather smaller than the largest lateral teeth, 

 the othf^r two subequal and considerably larger, the posterior one very 

 freely movable. These teeth are subject to some variation in different 

 individuals, and are seldom quite alike on both sides of the same fish. 



In the lower jaw is a single series corresponding to the fixed series in 

 the upper jaw. These are similarly enlarged in front, where the series 

 is partly duplicated and some of the teeth are movable. The teeth in 

 the lower jaw are broader and more directed backwards than those in 

 the upper jaw. 



MYLIOBATID^. 



48. Myliobatis californicus Gill. 



(Bhinoptera vespertilio Girard.) 



The commonest of the numerous stingrays in San Diego Bay. 

 DASYBATID^. 



49. Pteroplatea marmorata Cooper. 



Common in San Diego Bay. Probably distinct from P. Mrundo, hav- 

 ing a narrower disk and shorter tail, with distinct dermal fold above 

 and below. 



50. Urolophus halleri Cooper. 



Common. This species is certainly not identical with U. forpedinns, 

 in the synonymy of which species it is placed by Dr. GUnther. Its skin 

 is entirely smooth. It is probably a valid species, more nearly allied to 

 U. cruciatus than to U. torpedinus. 



51. Dasybatis dipterurus sp. nov. 



Allied to Basyhatis centrums and D. pastinaca. 



Disk rhomboid, slightly broader than long; anterior margins nearly 

 straight forwards, meeting in a very obtuse angle; posterior margins 

 curved ; lateral angles rounded. Tail nearly half longer than disk, with 



