158 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Disk broader than long; tip of snout slightly projecting. Anterior 

 margin of pectorals convex in front, then shallow concave, posterior 

 margin convex. Interorbital distance, measured on the bone, is con- 

 tained 3^ times in distance from tip of snout to a line connecting the 

 front margins of the orbits. Interocular space deeply concave in the 

 preserved specimen. 



Breadth of disk equals distance from tip of tail to shoulder-girdle. 

 Length of tail equals distance from its root to middle of eye. 



Tail nearly flat below with a well-marked lateral fold which is widest 

 posteriorly, but nowhere equals the height of the caudal. Caudal small, 

 its height (7™'") contained 3 times in its length (21™™). 



Mouth slightly arched, its width equal to 3 times the length of first dor- 

 sal base. Nasal flaps with a few fringes posteriorly. Distance between 

 nostrils contained 1^ times in their distance from tip of snout. Teeth 

 in 26 or 27 rows, with a short, moderately sharp median cusp, which is 

 occasionally much worn in the front of the jaws. 



The largest spiny bucklers on the back are 17 millimeters long at the 

 base. 



Snout above, supra-occipital region and the whole margin of pectorals 

 and ventrals covered with small prickles, as is also an area along the 

 tail, especially on its anterior half. Along the middle of the back and 

 the top of the tail is a row of 29 large spines. Between the dorsals is 

 a single large spine. Along the sides of the tail are spines a little larger 

 than those around the margin of the disk. The greater portion of the 

 disk is smooth. In a male, number 28098, of which we have portions 

 only, the bucklers are in about 22 rows, with 6 in a row at the widest 

 part; the claspers are slender and more than one-half as long as the tail. 



Under surface smooth, with the exception of an elliptical patch of 

 small spines near the tip of the snout. 



General color olive-brown above. There are numerous indistinct light 

 blotches on the disk, two of them larger than the rest ; the largest is 

 twice as long as the eye, and surrounds an inner blotch of white nearly 

 as long as the eye. There are two small light blotches, one on each side 

 of the tail, between the 17th and 18th spines of the median series. 



Measurements. 



Current number of specimen < 



Locality < 



(1753) 



27651 ? 



TJnalashk.a, 



Oct. 12, 1880. 



Millimeters. 



Extreme length 



Length of disk 



Body : 



Gi c.atest width of disk 



Givatcst width of tail at base* . . . 



Lcui;th of branchial area 



Width of branchial area in front . 



Width of branchial area behind. . 



975 

 507 



685 

 47 

 70 

 196 

 136 



