176 , Itejjorts and Proceedings — 



In this paper the author, after referring to the general question of the modification 

 of the structure of organic forms produced hy the action of external influences, indi- 

 cated that, in connexion with this, changes in the nature of the prey of carnivorous 

 animals ought to be taken into consideration. He inferred that cold-blooded aquatic 

 animals formed a much greater proportion of the food of Mesozoic than of Neozoic 

 Crocodiles, and pointed out as connected therewith the well-marked distinction 

 between the amphicoelian and procoelian type of vertebrae respectively characteristic 

 of the two groups. The procoelian character of the trunk-vertebrfe better adapts 

 that part of the body to be sustained and moved in air, and may be connected with 

 the incoming in Tertiary times of mammalian prey inducing the Crocodiles to rush 

 on shore. The Mesozoic Crocodiles were encased in a much stronger and more com- 

 plete dermal armour than their successors, doubtless for their protection from the 

 great Ichthyosaurs, Pliosaurs, etc., which coexisted with them ; but as these passed 

 away at the close of the Secondary epoch, the armour of the procoelian Crocodiles 

 has become more scanty, and the diminution of weight and rigidity thus caused would 

 favour progression in air, and the rapidity of movement required for capturing mam- 

 malian prey on land. The difference m the position of the palato-nares, and in other 

 related gular and palatal structures, between the Mesozoic and Neozoic Crocodiles, is 

 apparently connected with the power possessed by the latter of holding submerged a 

 powerful mammal without permitting the access of water to the posterior nostrils and 

 vrindpipe of the Crocodile ; and hence the author is inclined to ascribe a fish-diet 

 even to those massive-jawed Crocodiles from the Purbeck (such as GoniophoHs crass i- 

 dens and simus), which in some respects might seem fitted to grapple with large and 

 active mammals. The small size of the upper temporal apertures in Tertiary and 

 existing Ci-ocodiles is regarded by the author as a further proof in the same direction ; 

 these apertures are reduced by the progressive increase of the osseous roof of the 

 temporal vacuities, which again is correlated with increase in the bulk and power of 

 the temporal muscles, the main agents in biting and holding. The differences in the 

 length and strength of the jaw, as a rule, testify in the same direction. Further, 

 the fore-limbs in Mesozoic Crocodiles are shorter than in Neozoic species, indicating 

 that the former were more strictly aquatic in their habits ; the fore-limbs in all 

 Crocodiles being closely applied to the body during rapid swimming, and small limbs 

 being less obstructive than larger ones. On the other hand, they would be less 

 efficient as a means of progression on land, and hence it may be inferred that the 

 advent in Tertiary times of mammals frequenting the water-side, tempting the 

 Crocodiles to make a rush upon the land to seize such passing prey, would lead to 

 such sti'enuous action of the fore-limbs as would account for the increased size and 

 power of those organs in the Neozoic species. The author concluded with some 

 remarks upon the influence of the above considerations upon our views as to the 

 generic divisions of Crocodiles. 



3. " Notes on a Crocodilian Jaw from the Coral Eag of "Weymouth." By E. 

 Tully Newton, Esq., F.G.S., of H.M. Geological Survey. 



In this paper the author described what he believes to be a fragment of the lower 

 jaw of a Crocodilian, obtained from a greyish brown sandy grit, probably belonging 

 to bed 3 of Messrs. Blake and Hudleston's Sandford-Castle section. The specimen 

 measui-es about 1 1 inches long, and includes portions of both rami. The right ramus 

 contains- the remains of 1 2 alveoli, some of which, notably the first, second, fourth, 

 and fifth, contain fragments of teeth, which appear to have been directed very 

 obliquely outwards and forwards. The portion of the left ramus preserved gives 

 indications of 14 or 15 teeth. An impression of a tooth in the matrix gives a length 

 of \\ inch for the crown of the larger teeth ; their section was nearly round; but a 

 young unused tooth is slightly- compressed, with a distinct ridge running down each 

 side and two smaller ridges on the inner surface. The general surface of the crown 

 was covered with fine but distinct longitudinal ridges. The median area has a spindle- 

 shaped portion separated from the rest by deep grooves, the surface of which is longi- 

 tudinally grooved ; and this character, according to the author, does not occiu' in 

 either of the genera mentioned by M. Deslongchamps. 



4. " Note on Two Skulls from the Wealden and Purbeck Formations indicating a 

 new Subgroup of Crocodilia." By J. W. Hulke, Esq., F.E.S., F.G.S. 



The author described a Crocodilian skull obtained by Mr. H. "Willett, F.G.S. , 

 from the Hastings Sands near Cuckfield, in Sussex, and identified by that gentleman 

 with Goniopholis C7-assidens, Owen ; and another from the Purbecks near Swauage, 



