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 

 dorsal 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 Dieppe, in France, 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, which 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. 



