27» BULLETIN OF THE BUREAU OF FISHERIES. 



Thissmall ray is not infrequently taken in this region but is apparently never taken in large numbers. 

 Coles has taken a few nearly every year at Cape Lookout. 



Genus a£TOBATUS Blainville. 

 34. Aetobatus narinari (Euphrasen). Devilfish; spotted sting ray. 



Aetobatis narinari. Yarrow. 1877, p, 216: Jordan and Gilbert, 1879. p. 386. 

 Sloasodon narinari. Jordan. 1886. p. 26; Jenkins, 1887, p. 84. 



Aetobatus narinari. Smith. 1907, p. 46; Coles. 1910, p. 338-341; Gudger, 1912. p. 150: Coles, 1913, p. 29-32, fig. 1-2. pi. ra 

 (3 figures); Garman, 1913. p. 441, pi. 49, 54, 55, 57, 73; Gudger. 1914, p. 241. 323; Coles, 1914. p. 94. 



Teeth. — Teeth in a single row in each jaw; dental plate of lower jaw about twice as long as the upper 

 and about seven-ninths as wide; lower teeth strongly arched for\vard in the middle; upper teeth much 

 straighter, slightly bent backward at the sides. In a male 220.3 <^™- (7 f^^t, 2^ inches) long, there are 14 

 teeth in the upper jaw, 7 functioning, and 20 in the lower jaw, 13 functioning; in a male 291 cm. (9 feet 

 tyi inches) long, there are 23 teeth in upper jaw, 11 functioning; 29 in the lower jaw, 19 functioning; 

 functioning teeth more or less pitted. 



Skin smooth, one or more strong serrated spines on tail behind dorsal. 



Measurements and coloration of the male, 291 cm. long, taken with a dragnet by fishermen in 

 North River, May 28, 1914, furnished by Mr. Hildebrand. 



Tip of snout to posterior margin of ventrals, 134 cm. ; width of disk, 185 cm. ; interorbital , 23.5 cm. ; 

 eye, 3.8 cm.; snout, 22.8 cm.; width of mouth, 12 cm.; length of claspers, 40 cm.; length of dorsal 

 base, 6.0 cm.; height of dorsal, 6.0 cm. 



Color. — Upper surface very dark brown, almost black, with white spots or rings, or portions of 

 rings, some of these C-shaped, others form perfect circles, still others are in pairs connected by a 

 narrow isthmus of white; others are very close together, with only a slight stricture between them 00. 

 On the head and snout there are only roimd spots, no double spots or rings; the double spots are most 

 numerous just back of the head; following these on posterior part of back and along posterior margin of 

 disk are the rings; no transverse markingson body; tail plain black; ventral surface of body tmiformly 

 pale. 



The stomach contents were the bodies of clams, without any of the shells. 



In the specimen from Cape Lookout, 220.3 '^™- '°"gi whose length of disk to tip of ventrals was 74.3 

 cm., breadth of disk 106.8 cm., the jaws are barely half as large as in the specimen just described. 



In small individuals the white spots on dorsal surface are all circular, smaller than eye. 



This strikingly colored ray reaches a length of 12 feet or more. In the Beaufort region, where it is 

 quite common, it feeds almost exclusively on clams which it digs from the natural beds. As to its 

 method of getting the clams there still seems to be some difference of opinion. Owen (1840) advanced 

 the supposition that the projecting lower jaw was used like a spade for digging the shellfish out of tlie 

 sand. Coles (1910) and others state that the snout is used for this purpose. Gudger (1914) questions 

 this use of the snout, but advances no opinion as to the probable method used. 



The lower jaw projects beyond the upper, so that the front teeth of tlie upper jaw and the median 

 ones of the lower are used in crushing shells, as indicated by tlieir deeply pitted surfaces. The teeth 

 on the projecting portion of the lower jaw are smoother than the crushing teeth. Gudger (1914) noted 

 this difference, but offered no explanation for it. In the specimens at hand there are scratches or fur- 

 rows on this smoother surface extending fore and aft as if some sharp object had scratched the surface 

 in passing over it. The broken and irregular anterior margin of the jaw, the wearing down of the upper 

 surface until the pits characteristic of the teeth farther back have disappeared, and the presence of the 

 scratches convince the writer that Owen was correct and that the projecting lower jaw is used as a spade 

 for digging up clams on which the species feed. 



The stomach of the specimen 291 cm. long contained a considerable quantity of the meats of clams 

 without any pieces of shells. Coles states that as much as a gallon of clams has been taken from the 

 stomach of a single individual, and that the species is exceedingly destructive. The jaws of this species 

 are highly specialized, being used to dig the clams, to crush the shells, following which the meat is 

 separated from the shells. Coles has added some ver\' interesting observations to our knowledge of this 

 species, and more recently Gudger has written an extended review of the literatxu-e, together with addi- 

 tional data collected by himself at Beaufort and in Florida waters. This report is well illustrated. 



