40 
thrasher. 
iris blue, pupil green; nostrils small, not lobed; mouth five 
inches wide, shaped like a horse-shoe ; teeth flat, triangular, in 
two or three rows, not numerous; gill openings five. Pectoral 
fins wide at the base, pointed, eighteen inches and a half long. 
The body measured along the curve to the first dorsal fin two 
feet five inches, the fin triangular; from the first to the second 
dofsal fourteen inches and a half; this and the anal very small, 
which is an important part of the generic character, as assigned 
by Rafinesque and Swainson, the former being one and three 
quarters, and the latter one inch wide at the base; abdominal 
fins rather small, and triangular; above and below at the base 
of the tail a deep depression. Extreme breadth of the tail, 
including both lobes, thirteen inches ; the upper lobe narrow 
through its length: and at four inches from its extremity on 
the lower margin is a triangular process. Lateral line central 
and straight; skin smooth. Colour of the body and fins dark 
bluish, mottled with white over the belly. 
An example of this fish, taken in the Mount’s Bay, in Corn- 
wall, measured twelve feet in length, which may therefore be 
taken as about the usual length; but in November, 1799, 
an example was obtained at Dieqrpe, in Prance, as reported 
by Lacepede, which measured fifteen feet in length, and five 
feet in circumference; and which therefore exceeded in mag- 
nitude that which is described by Caius. Dr. Smith is 
reported to have discovered spiracles or temporal orifices, of 
very small size, whish therefore are named in the characters 
of the genus; but after search I was not able to find them. 
The colour seems to vary from a decided blue to dark, with 
little perceptible of the former colour; and it would also 
appear, if we are to be guided by the description given by 
Pennant, that some variation may also take place in the 
form of the tail; which he describes as passing straight 
backward, which was not the case in the example I have 
described. 
