470 



iiajid^t:. 



12. PSAMMOBATIS. 



Disk perfectly circular, the snout being very short and overlapped 

 by the anterior portions of the pectoral fins, which form the fore- 

 most part of the disk. Tail depressed, with a fold on each side ; 

 two small dorsal fins near its extremity, but without distinct ter- 

 minal fin. Each ventral fin is divided into two by a deep notch, 

 the anterior portion being narrow and enveloped in a very loose 

 skin. Each nostril with two nasal valves, the anterior forming a 

 sort of tube, the posterior triangular. Teeth obtuse. 



Southern coasts of South America. 



1. Psammobatis rndis. 



All the upper parts covered with minute spinous tubercles, placed 

 rather close together ; no larger tubercles on the disk, which has a 

 groove along the median line; a series of small thorns along the back 

 of the tail. Eyes rather small, their diameter being about equal to 

 the width of a spiracle. Mouth nearly straight, lower lip vertically 

 folded. The teeth of the upper jaw stand in about thirty-six scries. 

 The pectorals cover the anterior portion of the ventrals, but not the 

 posterior. Vent nearly in the middle of the total length. Brown, 

 with darker spots ; lower parts whitish. 



Southern coasts of South America. 



a. Sandy Point. Collected by Dr. Cunningham. 



Distance from the snout to the vent r5| inches. 



Length of the tail 3^ „ 



Width of the disk 5 



13. SYMPTERYGIA. 



Sympterygia, Miill. ^ Henle, p. 155. 



Tail very distinct from the disk, which is of rhombic shape, with 

 a fold on each side. Body rough or with spines. Two dorsal fins 

 on the tail, without spine. Tail with a rudimentary caudal fin. 

 The pectoral fins arc united in front, forming the fore part of the 

 snout ; ventral fins not divided 'nto two. Nasal valves as in Itaja. 



Hah. ? 



1. Sympterygia bonapartii. 



Miill. ^ Henle, p. 155, taf. 49. 



Snout somewhat pointed. A series of spines along the back and 

 tail. Brown, with round darker spots. (M. & H.) 

 Hah. ? 



14. PLATYRHINA. 



Platyrbina, Midi Sc Henle, p. 1 25. 

 Scarcely distinct from Sympterygia, from which it differs in 

 having the caudal fin well developed, and the ventral fins separate. 

 East Indies. 



