84 



SCIENCE 



[N. S. Vol. XXXIV. No. 864 



A Descriptive Catalogue of the Marine Rep- 

 tiles of the Oxford Clay. Part I. By Dr. 

 C. W. Andrews. Published by the British 

 Museum. 1910. 4to, pp. 1-205, pis. i-x. 

 The marine Jurassic formations of England 

 and Germany are exceptionally rich in fossils, 

 both vertebrate and invertebrate. There is 

 scarcely a museum in Europe and not many 

 in America in which the visitor fails to see 

 skeletons of iehthyosaurs, plesiosaurs or sea 

 crocodiles from one or another of the classic 

 localities. The British Museum collections of 

 Jurassic marine reptiles far surpass those of 

 any other institution, and preeminent among 

 them is the splendid series of Upper Jurassic 

 age, obtained from the clay-pits near Peter- 

 borough by Mr. Alfred Leeds. " Both in the 

 number of species represented," Dr. Andrews 

 observes, " and in the perfect preservation of 

 their remains, the Leeds collection far sur- 

 passes any other single collection of Mesozoic 

 vertebrates, especially one in which all the 

 specimens are from one horizon and from a 

 restricted area. Not only marine forms but 

 remains of terrestrial reptiles, including sev- 

 eral species of dinosaurs, have been obtained." 

 The completeness and abundance of the ma- 

 terial and fine preservation of the bones has 

 enabled the author to give a very thorough 

 description of the osteology of the principal 

 genera, and he has exercised a commendable 

 conservatism in the creation of new genera 

 and species. In the present volume the 

 iehthyosaurs and plesiosaurs are described; 

 the second volume will comprise the pliosaurs 

 and crocodiles. 



There is but one genus of iehthyosaurs, 

 Ophthalmosaurus, with which Baptanodon of 

 the Jurassic of Wyoming is regarded by the 

 author as congeneric. This is the most 

 highly specialized member of the order, with 

 extraordinarily large orbits, almost toothless, 

 with broad short forepaddle, and hindpaddle 

 much reduced in size. A swift and powerful 

 swimmer, proportioned like the modern por- 

 poises, it was also capable of diving to great 

 depths, as shown by the peculiarities of the 

 auditory apparatus, fitted to withstand great 



water pressure. In contrast to this swift 

 pelagic reptile, the plesiosaurs were rather slow 

 moving, comparable with the sea-turtles more 

 nearly than any other modern animal, and in 

 Dr. Andrews's opinion they lived mainly at 

 the surface and at no great distance from the 

 shore, and, as might be expected, show a much 

 greater variety in form than the iehthyosaurs. 

 All are referred to the Elasmosauridae, but in 

 Murmnosaurus the neck is greatly elongate, 

 the head relatively small and the whole animal 

 about twenty feet long; in Oryptocleidus the 

 neck is of more moderate proportions, the 

 head relatively larger and forepaddle broader, 

 while the total length is about twelve feet. 

 Two new genera, Picrocleidus and Tricleidus 

 are of intermediate proportions, but much 

 smaller size. The definitive generic charac- 

 ters are chiefly based upon the structure of 

 skull and shoulder girdle. The diversity of 

 form in these Upper Jurassic plesiosaurs is 

 much less than in their Cretacic successors, 

 best known from the western United States, 

 but they are decidedly more specialized than 

 the Lower Jurassic Plesiosaurus and its allies, 

 as is indicated in Dr. Andrews's reference of 

 all the genera to the Cretaceous family Elas- 

 mosauridfe, and most clearly demonstrated in 

 the progressive modification of the shoulder 

 girdle. 



Dr. Andrews's memoir is illustrated by ten 

 plates and over ninety line drawings in the 

 text, and by diagrammatic restorations of the 

 skeleton of the three best known genera and 

 a photograph of the mounted skeleton of 

 Oryptocleidus. It is in most respects very 

 near to the reviewer's ideal of what a mono- 

 graphic description ought to be — based upon 

 abundant and well-preserved material, the 

 amount and character of which is clearly 

 specified and listed in detail, well illustrated, 

 clear and concise in form, conservative in 

 nomenclature and species making, failing not 

 to distinguish fact from theory, certainty 

 from probability. The British Museum and 

 the author are to be congratulated upon the 

 appearance of this fine monograph. 



W. D. Matthew 



