38 NEW YOKK STATK MUSEUM 



torals largo; ventrals moderate; tail slender; a pit at the root 

 of the caudal; the caudal peduncle stronglj' keeled on each side; 

 caudal fin lunate, its two lobes nearly equal. Size large. 



17 Isurus dekayi (Gill) 

 Mackerel Shark 



Lamna punctata De Kay, N. Y. Fauna, Fishes, 352, pi. 63, figs. 206. 



207, 1S42 Cnot SqHfiliis punctrttns Mitciiill); Stoker, Hist. Fish. Mass. 



240, pi. XXX YII, fig. 1. lS(i7. (This is probably Lamna cormibim). 

 Isiiropsis (Jekayi Gill, Arm. X. Y. Lye. Nat. Hist. 153, 1861. 

 Isurus delxavi Jordan & Gilbert, Bull. 16, U. S. Xat. Mus. 874, 18S3; 



Jordan & Evermann, Bull. 47, U. S. Nat. Mus. 48, pi. YI, fig. 21, 1896. 



Body fusiform, cylindric. its greatest depth equaling one fifth 

 of the total length, and slightly exceeding the length of the 

 head. The caudal lobes are nearly equal in length, the upper 

 about ('(lual lo depth of body. Gill openings wide, the last 

 over ilic ant<'rior edge of the pectoral base; middle teeth very 

 long, much longer and narrower than the crowded, triangular 

 lateral teeth; first dorsal inserted behind pectorals at a distance 

 equal to one fourth of length of head; falcate, its base equal to 

 one third of its distance from tip of snout, its hight nearly one 

 eighth of the total length; pectoral falcate, more ihan one fifth 

 of total length, and longer than upper caudal lobe; anal and 

 second dorsal small; caudal keel nearly one fifth of total length; 

 deep pits at the root of the caudal above and below. 



Color dark slate, lighter beneath. De Kay was informed that 

 it is of a deep bottle green in life and the tongue is mottled with 

 black. Storer states that all the upper part of the body is 

 greenish, which becomes of a slate color after death; pupils 

 black; iris dusky. 



Tlic mackerel shark reaches the length of 10 feet. It occurs 

 from <';!]( Cod to the West Indies; but is rarely captured in 

 luost localities. 



Do Kay described a specimen 10 feet 2 inches long, taken in 

 New York liarboi-, October 1840. A somewhat smaller example 

 was ( aught n<:ii- the light-ship off Sandy Hook by Capt. C. H. 

 BarriiM<l n; years earlier Ihan the date of De Kay's description. 

 Storer refers to it as the most common species of shark found in 



