FISHES OF SINALOA. 393 



its width at a line in front of the nostril is as great as the 

 distance from its point to interlobular nasal emargination, 

 The rostro-frontal fontanelle is constricted at its anterior 

 third ; the interval between the crests of the anterior por- 

 tion enters about 2^ times in the interorbital area; at the 

 constriction, about 4 times; at the posterior portion, about 

 2^ times; the posterior portion gradually expands back- 

 wards and terminates with an oval contour behind. The 

 nasal lobes are about twice as long as wide, their length 

 externally exceeding half the length or breadth of the 

 rostral area. 



" The dental plate has a triangular contour; its anterior 

 angle obtusely rounded. 



"The dorsal commences immediately behind the pec- 

 toral fins. The ventral fins almost truncated behind, be- 

 tween the well rounded angles; their breadth 2^ times 

 their length. The tail is four or five times as long as the 

 body. 



"The color is bluish-black above, relieved on the head 

 by numerous, but rather distinct, whitish or yellowish 

 spots, smaller than eye, much larger on the body and be- 

 hind towards the sides, and on the ventrols sometimes as- 

 suming the form of ocelli ; below white ; pectorals mar- 

 gined with blackish. 



"This species is closely related to A. narinari and 

 its allies, and especially A. Jatirostris A. Dum., but is 

 apparently distinguished by the combination of charac- 

 ters given in the diagnosis. It belongs to the genus Gon- 

 iobatis 'Kg., proposed for a species with a more angular 

 lower dental plate than in A. narinari, and is related 

 to the Goniobatis meleagris Ag.* of the Sandwich Islands, 



* " This species has not been characterized, bnt a dried Aetobatine ob- 

 tained at the Sandwich Islands by the Wilkes Exploring Expedition prob- 

 ably belongs to it." 



2d Seb., Vol. V. ( 26 ) ' August 15, 1895. 



