270 HISTORY OF THE FISHES OF MASSACHUSETTS. 



Description. Body above, smooth, entirely destitute of spines, even on the dorsal 

 rido-e. Entire length, three feet eleven inches ; length, exclusive of the tail, one foot six 

 inches ; breadth across the pectorals, two feet five inches. Distance between the eyes, 

 four and a quarter inches ; eyes vertical, elliptical, greatest diameter one inch, least diame- 

 ter three quarters of an inch. On the summit of the orbit of each eye is a hard, blunt, 

 vertical projection, about one eighth of an inch in height, nearly white at the extremity. 

 The head is rounded anteriorly, and extends backward, widening but little, four and a half 

 inches, until opposite the eyes, where it joins the body. Mouth two inches in breadth, sit- 

 uated four inches posterior to the snout ; jaws lined with numerous blunt, tesselated teeth. 

 Nostrils about an inch and a half anterior to the mouth, each provided with a valve, and 

 having a depression or channel leading back almost to the corner of the mouth. Branch- 

 ial apertures live on each side ; distance between the anterior pair, four inches. Spiracles 

 situated behind the eyes, elliptical, one and a half inches in length. 



On the tail are two reversely serrated spines, one situated directly above the other, of 

 which the upper is the shorter ; their lengths are two and three fourths and three and 

 three fourths inches. Their insertion is at about five and a half inches from the origin of 

 the tail ; in color they are dingy white. Immediately before them is a small dorsal fin, 

 one and a half inches in length, and one inch in height. Tail very slender, smooth to 

 the tip, the inferior surface presenting no vestige whatever of fins. Anus beneath the 

 origin of the tail ; immediately posterior to it are two cylindrical, or slightly conic ap- 

 pendages, three and three fourth inches in length. As the specimen here described is the 

 only one which has fallen under my notice, I am of course unable to determine whether 

 all the characters which have been stated will prove to be constant. With respect to one, 

 the relative length of the two spines upon the tail, variation may probably be expected. 

 The upper spine will, in some instances, doubtless be the longer of the two. The speci- 

 men figured was apparently a male. 



Length, three to four feet. 



Remarks. In December, 1841,1 presented to the Boston Natural History Society, the 

 tail and portion of the jaw of a species of myliobatis which I had just received from Dr. 

 Yale of Holmes Hole, — and from two spines which were situated upon the tail, I pro- 

 posed the specific name of bispinosus. Mr. William 0. Ayres, then of Hartford, Connecti- 

 cut, afterwards found an entire specimen at Brookhaven, Long Island, and called it mylio- 

 batis acuta; this name, however, he withheld, and in his description of this species, pre- 

 fixed the name I had indicated, — at the same time remarking, " It is a very clearly 

 marked species, and as Dr. Storer was obliged to draw up his account from imperfect 



