17 FISHES OF SINALOA. 389 



margin of pectorals and on middle of back, leaving smooth 

 areas near middle of pectorals and over branchial arches; 

 16 to 20 large spinules along median line of back and 

 tail. 



Color, plain brown ; caudal fin darker, edged with 

 white. 



This species differs from Urolophus astcrias, in having 

 a wider disk, more acute snout, much smaller prickles, 

 and fewer spinules on back and tail. 



Three specimens obtained in the Astillero, the longest 



18 inches in entire length. Type, No. 1700, L. S. Jr. 

 U. Museum. 



This species is named for Dr. George Warren Rogers, 

 a scholarly physician, native of Vermont, but long resi- 

 dent in Mazatlan. 



16. Urolophus umbrifer Jordan & Starks n. sp. 

 Occasionally taken with Urolophus listerias, but much 



less common. 



Disk round, not wider than long, its length greater 

 than tail; snout pointed, not exserted. Snout from eye, 

 4^ in disk; eves equal to spiracles; mouth 2 in distance 

 to tip of snout; caudal spine inserted in front of middle 

 of tail; skin perfectly smooth. 



Color, brown above, with blackish cross-shades or bars, 

 radiating from the shoulder; a dark band behind eyes, 

 and one from eyes; caudal fin dark. 



One adult female specimen, the uterus containing four 

 young. 



This is probably not identical with Garman's Urolophus 

 nebulosus, being perfectly smooth and different in color. 



17. Dasyatis longus Garman. 



Rather common at Mazatlan, where specimens were 

 also taken by Dr. Gilbert; also recorded by Mr. Garman 



