56 Transactions of the 



tiou from the usual types of recent and fossil reptiles, uniting the 

 marks of a lacertian head, crocodile's teeth, to a neck of inordinate 

 length, with several modifications of the ribs, and four paddles of 

 enormous size. The most striking feature in the reptile is its 

 immense neck and comparatively small head ; there are from twenty 

 to forty vertebrae in the neck alone, which in some species is four 

 times the length of the head, and equal to the entire length of 

 the body and tail; while in one species (P. dolichodeirus) the 

 head is barely one-thirteenth of the skeleton. Few skulls have 

 been found perfect, but they are concluded to resemble in general 

 form those of crocodiles, but are much smaller. The teeth are 

 fixed in separate sockets, and there are about thirty or forty on 

 each side of the jaws. They are long, conical, slender, pointed, 

 slightly bent back, and longitudinally grooved from the base, 

 having one long fang. The pulp cavity is long and single, the 

 body of the tooth being firm dentine, the crown enamel, the base 

 cement. The paddles are composed of slender bones, and possess 

 considerable flexibility. These were air-breathing marine reptiles, 

 and obtained considerable expansion of the pulmonary cavities 

 by the gliding motion upon each other of the connecting bones of 

 the ribs in the region of the abdomen. 



Sixteen species of Plesiosaurus have been discovered in the Bri- 

 tish strata ranging from the lias to the chalk ; they are generally 

 to be met with in the lias and oolite. 



G. Dakyns next read a paper on " Cocoa." 



P. E. Ogle then read the following paper on — 



FLAME. 



Combustion in modern science is usually defined as chemical 

 action attended with evolution of light and heat. The familiar 

 forms of combustion consist of the union of the burning body 

 with the oxygen of the atmosphere. Most combustibles which 

 we meet with in common life consist almost entirely of carbon 

 and hydrogen ; these constituents on combustion in air are oxidised, 

 the former to carbonic acid, and the latter to aqueous vapour; and 

 since these products are entirely devoid of any sensible qualities, 

 and, being in a gaseous condition, are immediately removed from 

 the scene of action, it is easy to see how the notion arose of the 

 annihilation of the bm-ning body, and why the nature of the pro- 

 cess remained undiscovered for so long a period. 



The early attempts at an explanation of the phenomenon were 

 crude and unsatisfactory, but nevertheless exceedingly interesting. 

 An elemental body, called Fire, was supposed to exist, possessed 

 of the property of devouring curtain other bodies, and converting 



