238 



HISTORY OF THE FISHES 



MASSACHUSETTS 



GENUS VII. ZYG^ENA. Cuv. 



Head depressed, more or less truncated in front ; the sides extend horizontally to a 

 considerable length, with the eyes at the external lateral extremity. Teeth of the same 

 shape in the upper and lower jaw, namely, the points directed toward the corner of the 



th, with a smooth edge when y 



but distinctly serrated 



a 



dult 



specim 



Branchial openings, five. Two dorsal fins, — the first in a line close behind the pecto 

 rals : the second, over the anal fin. 



Zyqjesa Malleus, Val 



The Hammer-headed Shark. 



(Plate XXXVIII. Fig. 3.) a. Head beneath.) 



Zygoma, Hammer-headed Shark. Mitch. Trans 

 Malleus, Val. Mem. du Mus. D'Hist. Nat. v 



.. 



.< 



(t 



<t 



M 



The Hammer-headed Shark, Stoker, Bost. Journ. Nat. Hist 



Val., Synopsis, p. 256. 



Dekat, Report, p. 362. pi. 62, fig. 204. 



Color, 



The upper part of body a dark 'grayish brown, light 



sides ; beneath 



white ; posterior inferior parts of head, bluish ; anterior margin of head tinged with white. 



Description. Head somewhat rounded anteriorly, semicircular directly in front, with 



a smaller curve on each side of this, widely expanded and much compressed at sides. 



The external margin of the sides of the head rounded, having the eyes situated at their 



anterior extremity ; the anterior angle in front of the 



e J 



very prominent. 



The 



width of the head is equal to twice its length, and is also about the length of the upper 

 lobe of the caudal fin, and one fourth the length of the fish. The expanded sides of the 



The nostrils are situated beneath and front 

 of this angle, in the extremity of an emargination that extends along the smaller curves 



The posterior portion of the head is bordered by a stout, fleshy, 



head are two thirds the length of the head 



previously mentioned 

 and concave membrane 



The eyes are large and prominent. The mouth is situated be 



neath ; its posterior angles on a line with the posterior 

 rows of sharp teeth are seen 

 and have a prolonged base 



edg 



of the head 



Several 



in each j 



their points are directed toward the sides 



Branchial apertures, five. The under surface of the head 

 abounds m mucous pores, disposed in patches, the largest of which is of a triangular form, 

 and directly in front. 



