534 The True Sharks 



shark, or Lamna, as distinguished from the blue sharks and 

 white sharks allied to Carcharias (Carcharhinus}. 



The Lamnoid sharks agree with the cat-sharks in the absence 

 of nictitating membrane or third eyelid, but differ in the an- 

 terior insertion of the first dorsal fin, which is before the ven- 

 trals. Some of these sharks have the most highly specialized 

 teeth to be found among fishes, most effective as knives or as 

 scissors. Still others have the most highly specialized tails, 

 either long and flail-like, or short, broad, and muscular, fitting 

 the animal for swifter progression than is possible for any other 

 sharks. The Lamnoid families are especially numerous as 

 fossils, their teeth abounding in all suitable rock deposits from 

 Mesozoic times till now. Among the Lamnoid sharks numerous 

 families must be recognized. 



The most primitive is perhaps that of the Odontaspididce 

 (called CarchariidcB by some recent authors), now chiefly ex- 

 tinct, with the tail unequal and not keeled, and the teeth slender 

 and sharp, often with smaller cusps at their base. Odontaspis 

 and its relatives of the same genus are numerous, from the 

 Cretaceous onward, and three species are still extant, small 

 sharks of a voracious habit, living on sandy shores. Odon- 

 taspis littoralis (also known as Carcharias littoralis] is the com- 

 mon sand-shark of our Atlantic coast. Odontaspis taurus is 

 a similar form in the Mediterranean. 



Family Mitsukurinidae, the Goblin-sharks. Closely allied to 

 Odontaspis is the small family of Mitsukurinida, of which a single 

 living species is known. The teeth are like those of Odontaspis, 

 but the appearance is very different. 



The goblin-shark, or Tenguzame, Mitsukurina owstoni, is a 

 very large shark rarely taken in the Kuro Shi wo, or warm " Black 

 Current" of Japan. It is characterized by the development 

 of the snout into a long flat blade, extending far beyond the 

 mouth, much as in Polyodon and in certain Chimaeras. Several 

 specimens are now known, all taken by Capt. Alan Owston 

 of Yokohoma in Sagami Bay, Japan. The original specimen, 

 a young shark just born, was presented by him to Professor 

 Kakichi Mitsukuri of the University of Tokyo. From this 

 our figure was taken. The largest specimen now known is in 

 the United States National Museum and is fourteen feet in 



