520 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Rhinobatus planiceps. 



Gannan, 1880, Bull. Mns. Comp. Zool. No. 11, 168. 



Disk, including ventrals, rliombic, about one and a half times as long 

 as wide. Anterior borders of pectorals straight, more than twice as 

 long as -the convex posterior margins. Angles of pectorals rounded, 

 the hinder not extending farther than to the vent. Outer angle of 

 ventrals rounded, posterior acute. Head broad, flat. Eostral cartilage 

 medium, dilated at the extremity, with the ridges close together in the 

 anterior third of their length. Snout rather broad, with rounded ex- 

 tremity. Eyes moderate. Spiracle immediately behind the eye, smaller 

 than the orbit, with a single fold on the posterior side. Anterior nasal 

 valve not dilated, posterior two-lobed. Mouth nearly straight. Body 

 covered with shagreen above and below. Tail appearing as if continued 

 on the posterior portion of the abdomen, much depressed, with a fold ou 

 each side, bearing two elevated dorsals behind the ventrals and a cau- 

 dal with convex border at its extremity. Second dorsal distant from 

 the caudal the length of its base. Bases of the dorsals distant from 

 each other the length of the anterior borders. Scales larger over the 

 central portions of the disk. Compressed hooked spines in a median 

 row on back and tail, in two patches ou each shoulder, and a series 

 above each eye. On the young these spines are much more prominent 

 and regular in size than in the adult. Color brown; light between and 

 on each side of the rostral ridges; white below. Young specimens 

 with a number of small, round, white spots on each side of the dorsum. 



The following measurements are taken from a young male : 



Inches. 



Total length 19-0 



Snont to end of ventrals 10-2 



Snout to mouth 3. 5 



Width of pectorals 6.9 



Payta, Callao, and Galapagos Islands. 



Syrbhina. 



Characters in general those of EhinohaUis. Disk somewhat shorter 

 and broader. Nasal valves dilated and extending upon the interuarial 

 space. 



Syrrhina brevirostris. 



Mliller & Heule, 1841, Syst. Beschr. Plagiost. 114. 

 Disk, including the ventrals, rhombic, longer than wide ; width about 

 seven-eighths of the length. Anterior margins nearly straight, slightly 

 indented opposite the gill-openings, at the end of the snout forming an 

 angle of less than ninety degrees. Angles and posterior margins of 

 pectorals rounded. Ventrals rounded. Posterior angle rather blunt. 

 Head moderate ; crown concave. Snout short, shghtly rounded at the 

 tip ; length about twice the width of the head between the eyes. Eos- 

 tral ridges distant at the head, meeting at the end of the rostrum. Eye 



