64 Geological Society. 



on the paddle of the Turtle and webbed foot of the Crocodile ; but 

 they differ in the absence of subdivision by secondary longitudinal 

 impressions. The structure of the integument of the fin agrees, 

 therefore, with the known reptilian characters of the skeleton of the 

 Ichthyosaurus ; and, as the skin with its appendages gives a charac- 

 ter to the great primary groups of vertebrata, it might be expected 

 that the skin of the Ichthyosaurus would exhibit some of the cha- 

 racters of the integument of existing reptiles. 



In conclusion, Mr. Owen remarks, that the other new facts pre- 

 sented by the specimen, accord with the indications of the natural 

 affinities of the Ichthyosauri afforded by their less perishable re- 

 mains ; and that all the deviations from the reptilian structure of 

 the skeleton tend to the type of fishes and not to that of cetaceous 

 remains. 



Dec. 18, 1839. — A paper was first read, entitled "Description 

 of the fossil remains of a mammal, a bird, and a serpent, from the 

 London clay," by Richard Owen, Esq., F.R.S., F.G.S. 



The author commences by observing, that only a few months had 

 elapsed since the highest organic animal remains known to exist in 

 the London clay were those of reptiles and fishes ; and that the 

 danger of founding conclusions in Palaeontology from negative 

 evidence was perhaps never more strikingly illustrated than by the 

 fact, that the first scientifically determined relic of a warm-blooded 

 animal from that formation proved to belong to the highest order of 

 that class, if man be excepted ; and that besides those quadruma- 

 nous remains, there have since been discovered in the London clay 

 underlying the coralline crag, near Kyson, in Suffolk, teeth of cheiro- 

 ptera, and of a species probably belonging to the marsupial order*. 



Mr. Owen then proceeds to describe the fossils, the immediate 

 objects of the communication. 



1. The portion of the mammal was discovered by Mr. Richardson 

 in the cliffs of Studd Hill, near Heme Bay, and belongs to a new 

 and extinct genus of Pachydermata. It consists of a small mutilated 

 cranium about the size of that of a hare, containing the molar teeth 

 of the upper jaw nearly perfect, and the sockets of the canines. The 

 molars are seven in number on each side, and resemble more nearly 

 those of the Chseropotamus than of any other known genus of 

 existing or extinct mammalia. They present three distinct modifi- 

 cations of the grinding surface, and increase in complexity from 

 before backwards. The first and second spurious molars have simple 

 sub-compressed crowns, surmounted by a single median conical cusp, 

 with a small anterior and posterior tubercle at the outer side, and a 

 ridge along the inner side of its base. They are separated by an 

 interspace nearly equal to the antero-posterior diameter of the first 

 molar. The second and remaining molars are in close juxtaposition. 

 The third and fourth molars form the principal difference between 

 the dentition of the present genus and that of the Chseropotamus, 

 being larger and more complex in the grinding surface. They 



* See Annals of Nat. Hist. vol. iv. p. 189. 



