68 Royal Society of Edinburgh. 



principal modifications of the Saurian type, as exemplified in the 

 Crocodilian and Lacertine species ; and he points out many particulars 

 in which the Plesiosaurus deviates from the Loricate, and corresponds 

 with the Lacertine or Squamate group. Amongst these may be no- 

 ticed, the predominance of the elongated form in the cranial bones, 

 extending from point to point with wide interspaces, and giving to 

 the osseous fabric of the head the appearance of a scaffolding ; the 

 posterior bifurcation, mesial crista, and foramen of the parietal bone ; 

 the form and relative position of the posterior frontals, and especially 

 the absence of the ridge which, in the Crocodile, extends like a second 

 zygoma longitudinally across the zygomatic cavity. Mr. Owen fur- 

 ther dwelt upon the form and position of the zygomatic portion of 

 the temporal bone, the bony interspace of the external nostrils, the 

 structure of the lower jaw, and particularly on the existence of a wide 

 space on each side of the posterior region of the skull, bounded above 

 by the arch formed by the bifurcate processes of the parietal and the 

 tympanic bones, and opening into the temporal fossae, as evidences 

 of the affinity of the Plesiosaurus to the Lacertine Sauria. The cor- 

 respondence of the cranial organization of the Plesiosaurus to those of 

 the Crocodile, was noticed in the strength of the maxillary apparatus, 

 the general form and structure of the upper jaw, and in the nature 

 and alveolar lodgement of the teeth. The peculiarities of structure 

 referable to the special exigencies of the extinct form of Saurian under 

 consideration, were also dwelt upon, and, lastly, those which charac- 

 terized the species described, and which illustrate its more imme- 

 diate affinities, 



ROYAL SOCIETY OF EDINBURGH. 



April 9th. — Dr. Abercrombie, V.P., in the Chair. 



Sir Charles Bell read a paper " On the Comparison of the Nerves 

 of the Spine with those of the Encephalon." (Part ii.) 



As this paper bears more directly on physiology than zoology we 

 shall be the more brief. This part is chiefly occupied with the portio 

 dura of the 7th pair of nerves of the brain, which is peculiar in its 

 function, origin, and distribution. Instead of investigating its func- 

 tions by experiments, the author stated it could be more humanely 

 done by attentive observation on the living, and still more on the 

 dying ; it is pre-eminently a muscle of respiration, and its influence 

 was conspicuous on the countenance through the process of dissolu- 

 tion to the last sigh ; also in the highest state of excitement, mental 

 and bodily, and in the state of greatest repose. Though not a nerve 

 of pure sensation or volition, but of respiration, and although the 



