ROOM III. PLESIOSA.URUS DOLICHODEIRUS. 343 



derable expansion of the pulmonary cavities took place in these 

 air-breathing marine lizards. 



The bodies of the vertebrae are subcylindrical, and their 

 articular surfaces nearly flat ; there are two pits on the under 

 part ; the haemapophyses and costal processes are not anchy- 

 losed to the body ; and the haemapophyses consist of two 

 distinct laminae which do not coalesce distally into a spine, 

 and form a true chevron-bone. 1 



The paddles are composed of fewer and more slender bones 

 than in the Ichthyosaurus, and must have been of a more 

 elegant form, and of greater flexibility. The carpus consists 

 of a double row of round ossicles, which are succeeded by 

 elongated metacarpals, and these by slender and slightly- 

 curved phalangeal bones. 



PLESIOSAURUS DOLICHODEIRUS. Wall-case D. The specimen 

 on the top of this Case is invested with a classical interest, for 

 it was the subject of the admirable Memoir on this remarkable 

 genus by the present Dean of Llandaff, (the Rev. "VV. D. Cony- 

 beare,) on the Plesiosaurus dolichodeirus (long-necked}, read 

 before the Geological Society, Feb. 20, 1824, and published in 

 the " Geol. Trans." vol. i. New Series* In the Case below, 

 there is another specimen of the same species from Lyme Regis ; 

 it is nine feet in length, has the two right paddles, and exhibits 

 the under surface of the lower jaw. A third specimen of this 

 species, consisting of the trunk and paddles, is deposited in 

 the upper compartment of Case F. 



This species presents such extraordinary deviations from 

 the ordinary saurian type, in the great length of its neck, and 

 the extreme smallness of the head, that the correct inter- 

 pretation of its characters and affinities, at the dawn of 



1 For anatomical details consult " Brit. Assoc Report," 1839. 



2 This specimen is figured in "Geol. Trans." vol. i. new series, PI. 

 XL VI II. p. 381. It was discovered and developed by the late Mary 

 Anning, of Lyme Eegis, and purchased by the late Duke of Buckingham 

 for (I believe) 105?. I had the pleasure of being present when Mr. 

 Conybeare read the Memoir at the meeting of the Geological Society in 



4 Bedford Street, Covent Garden ; the specimen was placed in the narrow 

 vestibule at the entrance, for want of room. Some years afterwards I 

 saw it, in company with Dr. Buckland, at the princely mansion of the 

 Duke of Buckingham, at Stowe. On the dispersion of the treasures of 

 nature and art in that noble collection, it was bought for the British 

 Museum. 



