632 SCIENCE PROGRESS 



50, of which the first half-dozen or so are crowded together in 

 order to lie beneath the scapulae. Another feature is the sudden 

 downward bending of about fifty of the terminal vertebrae of 

 the tail to form the lower support of a vertical caudal fin, quite 

 different in structure from that of a fish. 



These Oxford Clay ichthyosaurs were practically toothless, 

 and thus different from their Liassic predecessors, which carried 

 a powerful dentition. This implies a difference in food, and as 

 the Oxfordian species were probably more pelagic in habit than 

 those of the Lias, they may have preyed on the contemporary 

 giant belemnites, whereas the earlier forms were largely fish- 

 eaters. As already noted, a similar difference distinguishes 

 the giant Cretaceous pterodactyles from their smaller Liassic 

 forerunners, and an analogous change of diet probably also 

 occurred in their case. 



The Lower Liassic plesiosaurs of Halverstadt form the 

 subject of an illustrated article by Dr. T. Brander in vol. lxi. 

 of the Palceontographica, but as the species belong to well- 

 known types, detailed notice is unnecessary. The name 

 Leurospondylus ultimus is proposed by Mr. Barnum Brown 

 (Bull. Amer. Mus. Nat. Hist. vol. xxxii. pp. 605-15) for a 

 new generic type of plesiosaurian from the Upper Cretaceous 

 Edmonton beds of Alberta, which is of special interest on 

 account of being the latest member of its order at present 

 known. It was a relatively small species — the vertebral column 

 measuring about 7 feet — and related to Elasmosaurus, among 

 its distinctive features being the medium length of the neck, 

 the shortness and width of the centra of the vertebrae, and 

 the single-headed ribs. 



In addition to the gift of the type skull of the perissodactyle 

 mammal Pliolophus vitlpiceps, to which allusion has been made 

 above, Mrs. Bull, widow of a late vicar of Harwich, has presented 

 to the British Museum (Natural History) a skull and three shells 

 of one or more of the three large species of marine turtles of 

 the genus Lytoloma which occur in the so-called septaria of the 

 London Clay of the Essex coast. In his above-mentioned report 

 on the Terra Nova fishes, Mr. Regan expresses the opinion that 

 the giant Tertiary horned tortoises of Queensland and Patagonia 

 represent, respectively, distinct generic types, and therefore lend 

 no support to the theory of a former land-bridge between those 

 areas. 



