144 Bulletin American Museum of Natural History. [Vol. XXXV, 



on tail; center of disk broadly whitish, sharply contrasted with the slate of the 

 pectorals, extending from about the middle of the snout backward to pelvic girdle 

 and irregularly at the sides onto the anterior lobes of the pelvic fins. 



Type No. 5198 American Museum of Natural History. Total length 29 inches. 

 Collected at Guadalupe Island, March 1, 1911. 



Our only specimen is an adult female with eggs, one of which measured 

 lj inches in diameter. 



Narcobatid.e. Electric Rays. 

 Narcine entemedor Jordan and Starks. 

 Agua Verde Bay, April 1, and Mulege, April 4, seined. 



Discopyge ommata Jordan and Gilbert. 

 Santa Cruz I., April 16, one specimen. 



DasyatidjE. Sting Rays. 



Urobatis concentricus sp. nov. 



Fig. 2. 



Disc subeircular, anterior edges straight, meeting at snout in an obtuse angle. 

 Breadth of disc about equal to length to base of tail. Tail to tip of caudal 1.4 in 

 length of disc. .Snout 4.5 in body to base of tail. Interorbital width 1.4 in snout. 

 Snout from eye equal to snout from mouth. Width of mouth 1.6 in distance to tip 

 of snout. Eye 4 in snout, equal to or slightly smaller than spiracle. 



Teeth small, numerous, tessellated, with acute triangular cusps. 



Tail with moderately developed lateral folds, extending backward to insertion of 

 spine, which is about midway between the pectoral axil and the tip of the caudal. 

 Caudal oblong, rounded at tip, its depth 2.5 in snout. Spine strong, retrorsely 

 serrate, its length on dorsal ridge equal to interorbital width. 



Skin everywhere smooth. Ground color in alcohol dark brown, broken into 

 coarse reticulations on middle of disc by large rounded pale spots which average in 

 diameter about one half the interorbital width. These spots are arranged more or 

 less definitely in 3 concentric circles around a central one in the middle of the disc 

 Two narrower pale unbroken bands, concentric with these, on the edge of the disc, 

 extending on the ventrals. Under side pale with a brown margin \ inch wide in a 

 specimen 17 in. long and extending forward to opposite mouth. Extreme margin 

 of disc and ventral fins pale. Under surface of tail pale, caudal dusky. 



Type No. 5199 Am. Mus. Nat. Hist. 



Length 17 inches, from the east side of Esteban Island, April 13, 1911. 



