KIMMERIDGIAN CROCODILES. 151 



between the organ of hearing and the palate, and showed that the ' foramen ' 

 which Olivier had described as giving passage to an artery was the medial outlet of 

 an eustachian canal, one by which the atmospheric air could pass to the tympanic 

 cavity. 



The foregoing details of the osteological and dental characters of the extinct 

 Crocodilian reptiles of the secondary or mesozoic formations, as well as those of 

 the tertiary Crocodiles in the first volume of the present work, testify how little 

 was left by Baron Cuvier to be added by his disciples and successors. The 

 combination of secondary and tertiaiy modifications in the structure of skull and 

 teeth, in the Kimmeridgian PlesiosucJms, will probably be esteemed as the chief 

 addition to this chapter of Extinct BeptUia. 



It owes to Geoffrey St. Hilaire the invention and application to genera, the 

 chai^acters of which are exclusively due to Cuvier, of names which the founder of 

 paleeontological science cared not to give. 



In my PL XX the two figures from the PI. VII of the " Ossemens Fossiles " 

 are repeated, which Geoffroy selected as characteristic of the genus he proposed to 

 term Steneosaurus. But the gist of the ' Memoires ' of 1825, as of those of 1830, was 

 to interpret the Cuvierian facts according to the Lamarckian evolutional hypothesis 

 of Species, which Geoffroy had adopted in the following terms : " La formation 

 successive et leur evolution dans le cours des figes." He then proceeds : — " Je 

 montrerai des formes remplacees insensiblement par d'autres, qui n'auraient pu 

 s'accommoder de I'ancien ordre des choses;" in other words, the battle of life 

 was against them. 



Reflecting on the Palseontologist who guided his course in the science, "par de 

 faits jwsitifs,"^ Geoffroy afl&rms, "qu'il renonce a ce qu'il y a de plus vif, de plus 

 enivrant, et de plus profondement philosophique dans la vie des sciences."" 



" Les modifications insensibles d'un siecle a uu autre finissent par s'ajouter et 

 se reunissent en une somme quelconque. Si ces modifications amenent des effets 

 nuisables, les animaux qui les eprouvent cessent d'exister, pour etre remplaces par 

 d'autres, avec des formes un peu changees, et changees a la convenauce des 

 circonstances." See also the ' Section ' entitled ' Le degre d'influence du Monde 

 ambiant pour modifier les formes animales,' 4eme Memoire, p. 79. 



Under this conviction Geofi'roy rejoiced to see the transitional step, though 

 short, which the extinct oolitic Crocodile, of " Quilly," his Steneosaurus, made 

 toward the modern Gavial. Still more exultant would have been his reception of 

 the form here described of an advance made in a secondary formation, nearer our 

 times, beyond the gangetic long-beaked Crocodile to the shorter and broader 

 cranial characters of the more numerous and widely distributed " Emydosaurians," 

 representing the existing genera Crocodllus and Alligator. 



1 ' Divers Memoires,' &c., p. 137. - lb., ib. 



