Oeological Society of London, 427 



fifteen feet of black and liglit-coloured shales full of fossils. The 

 beds appear to dip to the S.E. 



11. " The Eesemblances of Ichthyosaurian Bones to the Bones of 

 other Animals." By Harry Govier Seeley, Esq., F.L.S., F.G.S. 



Hitherto in comparative anatomy the term affinity has been 

 vaguely used in treating of the extinct groups. In this paper the 

 author endeavoured to give precision to the term Ichthyosaurian by 

 analyzing the characters of the Ichthyosaurian skeleton into the 

 resemblances which it presents to the skeletons of other vertebrates. 

 Ichthyosaurian characters are subdivided into Mammalian, Avian, 

 Crocodilian, Chelonian, Lacertilian, Cameleonian, Rhynchocephaliaii, 

 Ophidian, Urodelan, Piscine, Plesiosaurian, Dinosaurian, Dicynodont, 

 and Labyrinthodont. By thus classifying the characters it is antici- 

 pated that the affinities of the Ichthyosaurian type may be rendered 

 evident. 



12. " The Eesemblances of Plesiosaurian Bones vpith the Bones 

 of other Animals." By Harry Govier Seeley, Esq., F.L.S., F.G.S. 



This paper is an attempt to make a similar analysis of the Plesio- 

 saurian skeleton. 



13. '■'■ On the Tibia of Megalornis, a large Struthious Bird from 

 the London Clay." By Harry Govier Seeley, Esq., F.L.S., F.G.S. 



The author described the distal portion of a right tibia of a large 

 struthious bird from the London Clay of Eastchurch in Sheppey. 

 The only living types approximating to it are the Apteryx, vv^hich 

 similarly has the shaft at the back of the distal articulation, and the 

 Emu, which similarly has the shaft compressed from back to front. 

 The author considered that the skull named by Prof. Owen Dasorms 

 might, if it belonged to a bird, be referred to Megalornis ; bat he 

 detailed considerations which led him to suggest that Basornis may 

 possibly be a fish. 



14. " On Cervical and Dorsal Vertebrae of Crocodilus cantabrigiensis, 

 Seeley. from the Cambridge Upper Greensand." By Harry Govier 

 Seeley^ Esq., F.L.S., F.G.S. 



The author described in detail a cervical and a dorsal vertebra of 

 a proccBlous Crocodile from the Cambridge Upper Greensand, which 

 in the main presented the character of a young existing Crocodile 

 coupled with distinctive features. The centrum of the cervical ver- 

 tebra is oblique, and the neural canal of the dorsal vertebra is small 

 as in Hyposaiirus. The species is of small size. 



15. " On the Base of a large Lacertian Skull from the Potton 

 Sands." By Harry Govier Seeley, Esq., F.L.S., F.G.S. 



This specimen was interpreted by the author as the anchylosed basi- 

 occipital and basisphenoid of a Dinosaur. It showed a resemblance 

 to Crocodiles in its posterior aspect, but in all other respects was 

 Lacertian ; it makes a close approximation to Hatteria, and in no 

 respect shows affinitj'" to birds. The pterygoid processes look down- 

 ward, and the basioccipital condyle looks downward and backward. 

 The base of the brain-cavity is long and narrow, while its anterior 

 border corresponds to an imperfectly ossified fibro-cartilage seen in 



