126 REPORT— 1839. 



pelvic arches present are greater than in the corresponding parts 

 of the skeleton of the Ichthyosaurs, but those of the paddles 

 themselves appear to be fewer ; the number of carpal and tar- 

 sal bones varies from six to eight, but that of the digital ossi- 

 cles is much more constant than in the Ichthyosaurs. 



With respect to the geological relations of the Enaliosauria, 

 or the extent of strata through vrhich their relics have been 

 traced, my researches are merely confirmatory of the generali- 

 zations already enunciated by Messrs. Conybeare and Buck- 

 land. The British Enaliosaurs extend through the vi^hole of the 

 oolitic period, including the lias and oolite proper to the weal- 

 den and chalk formations, the most recent depositary being the 

 chalk marl, in which Ichthyosaurian remains have been dis- 

 covered by Dr. Mantell, at Dover ; Dr. Buckland has found 

 similar remains in the Gault, near Benson, Oxon ; and I have 

 seen the humerus of a Plesiosaurus from the Gault, near Maid- 

 stone. 



The following are the names of the species of Enaliosauriaj 

 in the order in which they are described in the foregoing 

 Report : — 



1. Plesiosaurus Hawkinsii, Owen. 



2. — dolichodeirus, Conybeare. 



3. macrocephalus, Con. 



4. brachycephaluSf O. 



5. niacronms, O. 



6. pachyonius, O. 



7. arcuatus, O. 



8. subtrigonus, O. 



9. trig-onus, Cuvier. 



10. brachyspondylus, O. 



11. costatus, O. 



12. dcedicomuSf O. 



13. rugosus, O. 



14. grandis, O. 



15. trochanterius, O. 



16. " ajinis, O. 



1. Ichthyosaurus communis. Con. 



2. intermedius, Con. 



3. platyodon, Con. 



4. ■ lonchiodon, (). 



5. tenuirostris, Con. 



6. : — acutirostris, O. 



7. latifrons, Kcenig. 



8. latimanus, O. 



9. thyreospondylus, O. 



10. trigonus, O. 



