488 Mr. A. S. Woodward on Scapanorhynchus. 



and the great extent of the anal fin, seemed to justify at 

 least its generic separation. At the same time it was 

 suggested that many so-called teeth of Odontaspis from the 

 Cretaceous formations of other parts of the world might 

 truly belong to Scapanorhynchus, and in that case would 

 indicate the very wide distribution of this shark in the seas 

 at the close of the Mesozoic era. It was also remarked that 

 while all the teeth in the two typical species from the Lebanon 

 seemed to bear a pair of lateral denticles, the hinder teeth 

 alone possessed these denticles in certain other species, 

 e. g., in Scapanorhynchus rhaphiodon from the European 

 Chalk *. 



Within the last ten years nothing of importance has been 

 added to our knowledge of the Cretaceous Scapanorhynchus ; 

 but quite recently, in the present writer's opinion, new in- 

 formation on the subject has come from an unexpected source. 

 A shark in all essential respects identical with the supposed 

 extinct genus in question has been described by Dr. I). S. 

 Jordan f from the deep sea off Yokohama, Japan. It was 

 obtained from a fisherman by Mr. Allen Owston, of Yokohama, 

 and presented by him to the Zoological Museum of the 

 University of Tokio. It was lent to Dr. Jordan for 

 description by Prof. Mitsukuri, and has received the new 

 generic and specific name, Mitsukurina Owstoni. The shark 

 is recognized by Dr. Jordan as more nearly related to 

 Odontaspis than to any other surviving genus ; but, for 

 reasons not definitely formulated, it is considered to be the 

 type of a distinct family, Mitsukurinidas. 



The Lebanon fossils, of course, are marred by many 

 imperfections; but it appears that, in all the generic characters 

 which can be compared, the living Mitsukurina agrees with 

 the Cretaceous Scapanorhynchus. Generic differences may 

 still be found, but they have yet to be pointed out. Like 

 that of the recent fish, the skeleton of the fossil may be 

 appropriately described as flexible. The elongated rostrum 

 is identical in the two cases, only relatively longer in the 

 extinct species from Mount Lebanon. The fossils naturally 

 do not exhibit the peculiar indentation between the mouth 

 and the rostrum. One specimen of Scapanorhynchus Lewisi 

 (Brit. Mus. no. 49474) clearly shows four branchial clefts 

 immediately in front of the pectoral fin, so that the fifth 



* See especially figures by A. S. Woodward, " Notes on the Sharks' 

 Teeth from British Cretaceous Formations," Proc. Geol. Assoc, vol. xiii. 

 (1894), p. 196, pi. v. figs. 11-13. 



t D. S. Jordan, " Description of a Species of Fish (Mitsukurina 

 Owstoni) from Japan, the Type of a Distinct Family of Lamnoid Sharks/' 

 Proc. California Acad. Sci. [3] Zool. vol. i. no. 6 (1898). 



