21 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. nariznarz and 
its allies, and especially A. /aterostras A. Dum., but is 
apparently distinguished by the combination of charac- 
ters given in the diagnosis. It belongs to the genus Gon- 
zobatis Ag., proposed for a species with a more angular 
lower dental plate than in A. narznarz, and is related 
to the Gonzobatis meleagris Ag.* of the Sandwich Islands, 

*«This species has not been characterized, but a dried Aétobatine ob- 
tained at the Sandwich Islands by the Wilkes Exploring Expedition prob- 
ably belongs to it.” 
2p SER., VoL. V. ( 26 ) August 15, 1895. 
