102 • BBPORT--1841. 



vertical section, with the angles slightly rounded ; the expanded articular ends 

 are subcircular. A fractured dorsal or lumbar vertebra, from the same locality, 

 ■with transverse processes extending obliquely backwards from the upper part 

 of the sides of the body, measures one foot across the nearly flat articular sur- 

 face. The body of a caudal vertebra of the same species, from the Portland 

 stone at Thame, measures seven inches four lines in antero-posterior diameter ; 

 six inches six lines in transverse diameter ; and seven inches eight lines in ver- 

 tical diameter. The under surface is concave lengthwise, and nearly flat from 

 side to side ; it is perforated by many large vascular canals. A third caudal 

 vertebra is somewhat shorter in antero-posterior diameter, but exceeds the pre- 

 ceding in vertical diameter, which is eight inches. In all these vertebrae the 

 neurapophyses are anchylosed to the centrum, and have a smaller antero-pos- 

 terior extent at their base than the centrum, as in the preceding species of 

 Cetiosaurus. In all the species the haemapophyses are articulated to the in- 

 terspaces of two vertebree. To the Cetiosaurus longus is referable a vertebra, 

 eight inches in length of body, and nine inches in transverse diameter, from 

 the Yorkshire oolite at White Nab, which, together with some metatarsal bones, 

 are deposited in the museum at Scarborough. No teeth, or fragments of jaws 

 or cranium, have hitherto been discovered, which can, with certainty, be re- 

 ferred to any of the preceding species. 



The names which I propose to give to these species refer to the relative 

 length of their vertebrae, and from what we know of the constancy and re- 

 gularity of this dimension in the back bone of individuals of the same species 

 of Saurian, these specific names would, if we had the entire animals, be found 

 to be as appropriate in reference to the relative length of their whole bodies. 



At present the Cetiosaurus brevis is known to me only by specimens from 

 the Wealden strata ; the Cetiosaurus medius by fossils from the lower oolite, 

 and the Cetiosaurus longus by a few vertebrae from both the upper and the 

 lower oolite ; but how far these species should actually characterize these 

 divisions of the great oolitic system, will depend on the results of ulterior 

 researches and a longer experience. It is certain, however, that we have in 

 these remains ample proof of the existence, at that period of the earth's his- 

 tory which has been aptly termed the 'Age of Reptiles,' of another gigantic 

 genus in addition to the Pliosaurus, Poikilopleuron, Streptospoiidylus, Igua- 

 nodon, Megalosaurus and Hylceosaurus. 



The enormous Cetiosauri, some of which must have rivalled the modern 

 whales in bulk, may be presumed to have been of strictly aquatic and most 

 probably of marine habits, on the evidence of the sub-biconcave structure of 

 the vertebrae, and of the coarse cancellous tissue of the long bones, which 

 show no trace of medullary cavity. In the great expanse of the coracoid and 

 pubic bones, as compared with the Teleosaurs and Crocodiles, the gigantic 

 Saurians in question manifested their closer affinity to the Enaliosauria : 

 their essential adherence to the Crocodilian type is marked by the form of the 

 long bones of the extremities, especially the metatarsals ; and, above all, by 

 the toes being terminated by strong claws. The main organ of swimming is 

 shown, by the strength and texture, and vertical compression of the poste- 

 rior caudal vertebras, to have been a broad vertical tail : and the webbed feet, 

 probably, were used only partially in regulating the course of the swimmer, 

 as in the puny Amblyrhynchus of the Gallipagos Islands, the sole known ex- 

 ample of a Saurian of marine habits at the present period. 



DINOSAURIANS. 



This group, which includes at least three well-established genera of Sau- 

 rians, is characterized by a large sacrum composed of five anchylosed ver- 



