470 kajtd.t;. 



12. PSAMMOBATIS. 



Disk perfectly circular, the snout being very short and overlapped 

 by the anterior portions of the pectoral fins, -u-hich 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 enveloj^ed 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 rudis. 



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 

 postei-ior. Tent 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 'Sf inches. 



Length of the tail ^f ,, 



Width of the disk 5 ,, 



13. SYMPTERYGIA. 



Sympterygia, Miill. ^- llenh, p. 1.55. 

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

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

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

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

 snout ; ventral fins not di\'idcd into two. Nasal valves as in Eaja. 



Hah. ? 



1. Sympterygia bonapartii. 



Mull. <5- Henle, p. 155, taf. 49. 

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

 tail. Brown, with round darker spots. (J/, if- E.) 

 Hah. ? 



14. PLATYRHINA. 



Platyvhina, Milll. iV Ilenle, p. 125. 

 Scarcely distinct from S)/mjiteri/gia, from which it diifers in 

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

 East Indies. 



