THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE III. VOL. IX. 



No. XII.— DECEMBER, 1892. 



o:rxg-xi<tj^Xj .A.^eTiCLES. 



I. — Descbiption of the Cretaceous Saw-Fish 



SCLERORUYNCHUS ATAVUS. 

 By Arthur Smith Woodward, F.L.S., F.G.S. 



N the " Catalogue of Fossil Fishes in the British Museum " 

 (pt. i. 1889, p. 76, pi. iii. fig. 1), the imperfect rostrum of a 

 Selachian fiish from the Upper Cretaceous of Mount Lebanon was 

 described under the new generic and specific name of Schrorhynchus 

 atavus. Presenting some resemblances to the rostrum both of the 

 typical saw-fish (Pristis) and of Pristiophorus, hesitation was ex- 

 pressed in determining the systematic position of the genus to which 

 the fossil pertained ; but from the apparently complex nature of the 

 rostral cartilages and the absence of extended prepalatines, it was 

 deemed advisable to place the fish provisionally in the family of 

 Pristid?B. A further description of the extremity of the rostrum in 

 1889,' though pointing to no definite conclusion, also appeared to 

 favour the same view ; and the unexpected discovery of another 

 piece of rostrum among the Teleostean fishes in the British Museum 

 at the same time led the writer to hope that the trunk of Sclero- 

 rhynchiis might soon be identified. A careful study of the new 

 specimen in the light of other Lebanon fossils in the British Museum, 

 has at last realized this hope, and the affinities of Sclerorhynchus 

 atavus may now be discussed on the basis of a tolerably complete 

 skeleton. 



As some of the principal specimens under discussion have already 

 been described and figured, it will suffice on the present occasion 

 merely to publish the accompanying restored outline of the fish 

 (see p. 531). The trunk proves to be that already described under 

 the name of Squatina crassidens ; ^ and the discrepancies in the 

 dentition and branchial apparatus between this fish and the typical 

 Squatina, noted in the original description are thus explained. The 

 absence of all indications of the freely ascending portions of the 

 jiectoral arch is also noteworthy in this connection; though the arch 

 is not well shown under any circumstances. 



Enumeration op Specimens. 



Before, however, dealing with the skeletal characters of Sclero- 

 rhynchus, it is necessary to state precisely the nature of the evidence 



1 Proc. Zool. Soc. 1889, pp. 449-451, woodcut. 



2 Qatal. Foss. P'ishes, B.M., pt. i. 1889, p. 69, pi. ii. 



DECADE III. — VOL. IX. NO. XII. 34 



