68 
BULLETIN OF THE BUREAU OF FISHERIES 
mouth 1.67 to 2.05; interorbital (bone) 2.1 to 2.45; eye 3.6 to 5 in snout; spiracle in a quadrangular 
pit immediately back of eye, no tentacle on its posterior margin, the slit equal to diameter of eye; 
teeth in numerous rows, about 75 to 100 in each jaw, arranged in definite series like bricks in a 
pavement, the teeth slightly spear-shaped, each tooth with a broad base and an elongate, sharp 
cusp; skin entirely smooth in specimens at hand, large individuals are reported to bear caudal 
spines; tail very short, pointed, with a keel above and below, its length 4.07 to 4.95 in total length; 
ventral fins rather narrow, inserted notably in advance of the posterior margin of the disk, the pos- 
terior margins rounded; claspers of the male long and narrow, reaching half their length beyond 
posterior margin of ventrals in specimens 14J/£ inches broad. 
Color variable, gray, brown, light green, or purple above, with vermiculations and punc- 
tulations of lighter and darker colors; the tail lighter than body, with three or four dark bars; the 
anterolateral margins of disk frequently with roundish spots; lower parts plain white, outer 
margin of wings sometimes grayish, dusky, or salmon. 
The foregoing description is based on six specimens— four males and two females — ranging 
in length from 175 to 270 millimeters (7 to 10^4 inches) and in width from 265 to 375 millimeters 
(10}^ to 14 % inches), and the jaws with the teeth of a female, which, according to field measure- 
ments, was approximately 595 millimeters (23^ inches) long and 860 millimeters (34 inches) 
broad. This skate is characterized by the very broad body, the short tail, and by the absence 
of a tentacle behind the spiracle, or breathing hole, situated just behind the eye. 
This skate is taken in Chesapeake Bay from May until November. In September and early 
in October of 1921 numerous specimens were taken in pound nets in Lynnhaven Roads, where the 
latest catch was made on November 28. As many as 40 individuals were frequently caught by 
one net during a 24-hour period. It is probable that this skate migrates southward at this season 
of the year, returning from the more northerly feeding grounds in the bay. Most of the individuals 
taken in pound nets were of small size, specimens ranging from 10 to 13 inches in width predomi- 
nating. At Ocean View, Va., however, only three small specimens, 103^ to 10% inches in width, 
were taken in commercial and collecting seines from September 25 to October 27, 1922. This 
skate and the sting ray ( Dasyatis say ) appear to be about equally common. 
Little is known of the food of this species, but it is known to feed on crabs (Sumner, Osborne, 
and Cole, 1913, p. 739) and no doubt also on other crustaceans. The teeth appear to be too weak 
to crush oysters and clams. The stomachs examined, taken from specimens caught in a pound 
net, were empty. 
The species is viviparous and the normal number of young produced appears to be two, the 
greatest width of the young at birth being 6 inches (Smith, 1907, p. 45). The frequent presence 
of this species on sandy shores has caused it to be named “sand skate,” and it is called “butterfly 
ray” in allusion to the very broad, winglike expansion of the pectoral fins. The “wings” of this 
species are utilized to a limited extent as crab bait in the crab industry on Chesapeake Bay. 
This species is reported to reach a length of 4 feet (Smith, 1907, p. 45), also 15 to 18 feet 
(Uhler and Lugger, 1876). The largest individual mentioned in the field notes of the collectors 
of the present collection is the specimen previously mentioned measuring 23)^ inches in length. 
Habitat . — Cape Cod to Brazil. 
Chesapeake localities— {a) Previous records: Cape Charles; “vicinity of Norfolk, Va.” 
(Moseley, 1877, p. 9.) ( b ) Specimens in collection or observed in the field were taken at Back 
River, Ocean View, Lynnhaven Roads, and Cape Charles, Va., during May, June, September, 
October, and November. 
Family XIII. — MYLlOBATIMi. The eagle rays 
Disk broad; pectoral fins not continued to the end of the snout, but ceasing at side of head; 
a pair of rostral fins joined in front of head, supported by fin rays; tail long and slender, bearing a 
dorsal fin and usually a strong serrated spine on its basal portion; eyes large, lateral; spiracles 
large, behind eyes; teeth broad, flat, tessellated, the median ones usually broader than the others. 
