542 Storer on the 
the bottom, there sluggishly seeking its prey. 
Skin rough, beset with triangular, curved, striated 
and pointed asperities. Color of the entire body, a 
pale lead gray, somewhat darker on the back.” 
I have not had the good fortune to see a speci- 
men of the nurse, or to meet with a fisherman 
who knew any thing respecting it. Itis not, how- 
ever, at all surprising, that it should be unknown ; 
with most of our fishermen, a shark is a shark, 
without regard to specific names. The “hammer 
head," and “thresher,” and “mackerel shark,” are, 
it is true, known to many of them ; but so little 
do they feel interested in any species of fish which 
is not marketable, that they take no notice of 
their distinguishing characters ; and a species might 
often frequent our waters without being known, 
unless it differed exceedingly from a common fish. 
Fawrrv II. 
RAIIDAE. 
Er. Rar. Cuv. 
Generic characters. Form of the body rhom- 
boidal, very much depressed ; tail long and slender, 
rally armed on the upper surface with one or 
' rows of sharp spines ; two small fins near the 
end of the tail, and sometimes a small terminal or 
caudal fim; the eyes and temporal orifices on the 
upper surfice of the head ; nostrils, mouth and bran- 
chial apertures, beneath ; teeth flattened, lozenge 
- Shaped, the inner angle elongated in old males. 
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