684 SCIENCE PROGRESS 



concludes with a review of the extinct rhynchocephalians and 

 their relationships. 



Before noticing papers on marine reptiles, I may remind 

 my readers that interesting observations on mosasaurians, ich- 

 thyosaurs, turtles, etc., will be found in Dr. Stromer's article 

 on marine lung-breathing animals already quoted (p. Gy^,) in 

 connection with sirenians and cetaceans. 



Of the mosasaurian genus Tylosaurus Dr. von Huene de- 

 scribes a finely preserved skeleton from the Cretaceous of 

 Kansas in Geol. ii. Pal. Abhand., ser. 2, vol. viii. pt. 6. Several 

 osteological questions are discussed ; and since Tylosaurus 

 and another mosasaur possess rudimentary nasals, it is evident 

 that these bones are not involved in the premaxillary rostrum 

 of that group. The evidence of the existence of distinct nasals 

 is, however, questioned by Mr. S. W. Williston in a note on 

 a skeleton of the allied genus Platecarpus which appeared in the 

 Journal of Geology, vol. xviii. pp. 537-41. 



The first part of the British Museum Catalogue of the Marine 

 Reptiles of the Oxford Clay, based on the Leeds' Collection, by 

 Dr. C. W. Andrews, is a work of first-class importance. The 

 remains of crocodiles, ichthyosaurians and plesiosaurians from 

 the Oxford Clay near Peterborough collected by the Messrs. 

 Leeds are noted for their wonderful state of preservation, which 

 admits of the osteology of these groups being studied in nearly 

 as much detail as if we had recent skeletons. Although the 

 deposits at Peterborough were probably laid down in fairly 

 deep water, the association of bones of land reptiles with those 

 of the marine types indicates that the coast was not far distant. 

 Among the ichthyosaurs, the single large-eyed representative 

 of the genus Ophthalmosaurus was, however, a pelagic reptile 

 with habits doubtless very similar to those of the whales and 

 porpoises which have taken its place in the seas of the present 

 day. The absence of teeth may be due to the circumstance 

 that Ophthalmosaurus, like the modern beaked whales {Ziphiidce), 

 which are also nearly edentulous, fed on squids and cuttles — 

 a suggestion confirmed by indications in the skull of diving 

 powers on the part of these reptiles. 



The plesiosaurs of the Oxford Clay, in place of being driven 

 through the water at a rapid pace by means of a screw-like 

 tail-fin, after the fashion of the ophthalmosaur, appear to have 

 rowed themselves along on or near the surface in a more leisurely 



