the Fishes of Massachusetts. 185 



I remarked in my Report, that Dr. Yale informed me that a 

 species of Zygjena was found at Hohiies' Hole, 



Within a few weeks, Winslow Lewis, Esq., brought a fish 

 of this genus from Chatham, Cape Cod, ; t which place it was 

 taken with a second specimen, in a net. It was considered 

 by the fishermen there, as a great curiosity. 1 have been 

 kindly presented with the specimen, which now lies before 

 you, and would offer the following description. 



Zycena malleus. Yalenc. The hammer-headed Shark. 



ZygcBTia malleus. Valenciennes; Memoires du Mus. d'Hist. Nat. t. IV. p. 

 122. et fig. 



The entire length of the specimen is two feet and four 

 inches. All the upper part of the body is of a dark greyish 

 brown color : beneath, it is hg liter. The length of the head 

 is three inches, it is rounded anteriorly, very much compress- 

 ed at its sides, convex at the occiput. The greatest width 

 across the head, is nine inches : the external margins of the 

 sides of the head are rounded, having the eyes situated at 

 their anterior extremity : in front of the eyes, the anterior 

 angle is quite prominent, beneath this angle, in a slight emar- 

 gination, are situated the nostrils : the posterior portion of the 

 sides of the head, is bordered by a membrane. The eyes 

 are prominent and six lines in diameter. The QJiouth is sit- 

 uated beneath, two inches back of the snout, and measures 

 across from the angles, a little more than two inches. The 

 teeth are numerous in both jaws, sharp and triangular, having 

 a prolonged base. There are five branchial apertures u]X)n 

 each side — the anterior is the largest. 



The first dorsal fin, which is triangular, is situated a little 

 less than three inches back of the head, behind the pectoral 

 fins. 



The second dorsal fin is quite small, rounded at its upper pos- 

 terior extremity, and elongated at its lower posterior extremi- 

 ity into almost a filament : this fin arises about three inches 

 in front of the caudal fin. 



The pectoral fins, which are triangular, arise at the base of 

 the fourth branchial orifice. 



24 



