28o Papers from the Marine Biological Laboratory at Tortugas. 



My largest and most perfect specimen from Beaufort had a length 

 of 26.5 inches and a tail measuring but 27.8 inches, the ratio being i : 1.05. 

 This tail had plainly suffered amputation, as had the tail of four spines 

 elsewhere referred to. Both were enlarged and bent at the tip, the extreme 

 point being somewhat smaller than the part just anterior to it. Both some- 

 what resemble fingers amputated beyond the last joint. Only the very young 

 rays have fine slender tails. 



My largest Key West specimen, which was a full-grown male, was 3^ 

 feet long and possessed a tail 6 feet 10 inches long; the ratio being i : 1.9. 

 For so large a ray this one had a very long and slender tail, but about 

 midway of its length there is a very prominent knot, showing that it had 

 been broken but had grown together again. Still further back is a marked 

 bend, showing that it had been injured there also. The tip itself looks as if 

 it had been abbreviated. 



Annandale (1910) found the back and tail of a large female A. narinari 

 from the Bay of Bengal to be studded with "small star-shaped denticles. 

 On the head these are sufficiently close together to form a regular pavement, 

 while on the tail they have a spinous character." Nothing of the kind has 

 ever been noticed on any of my specimens, not even on the largest, but 

 Jordan and Evermann (1898), in describing Myliohatis asperrimus from 

 Panama Bay, say that it has the greater part of the dorsal surface of the 

 body and tail covered with minute stellate prickles. 



HEAD AND SNOUT. 



Jordan and Evermann's figures of Aetobatus narinari are possibly the 

 best we have, but compared with those found in this paper they show cer- 

 tain marked differences in the head region. In their drawing the head seems 

 to stand sharply above the level of the body, but the photographic lateral 

 view (fig. 13, plate vi) shows that this is not true, the body in the head region 

 being slightly thinner than it is further back. In the drawing the lower and 

 outer edges of the spiracles are much more strongly marked than in the 

 photographs. In the living fish there is little or no line of demarcation; 

 the skin continues from the dorsal surface of the body into the spiracle 

 without break, as is attested by the fact that spots are found within its 

 cavity. Various figures (on plate vi) show this admirably. 



In the drawing the eyes show very prominently; in the photograph 

 (fig. I, plate i) as in the five living or just dead and the four preserved speci- 

 mens examined by the writer, they are not visible from above since they are 

 hidden by the lateral projections of the head in front of the spiracles. In 

 Dumeril's drawing from the preserved specimen they are barely visible 

 (fig. 8, plate iv). 



In the photograph (fig. i, plate i) the snout is seen to be pointed and 

 of moderate length. Being below the general level of the body region, and 

 the camera being focused on the mid-dorsal region, the head is not shown to 

 best advantage, being somewhat foreshortened. However, the ventral view 



