482 Geological Society. 



OEOLOGICAL SOCIETY. 



[Continued from p. 166.] 

 November 5, 1856. — Colonel Portlock, President, in the Chair. 



The following communication was read : — 



" On the Stereognathus Ooliticus, from the Stonesfield-slate.'* 

 By Prof. Owen, F.R.S., F.G.S. 



The subject of this paper was a small mammal, represented by a 

 fragment of a lower jaw retaining three molar teeth, which was ob- 

 tained by the Rev. J. Dennis from the Stonesfield-slate of Oxford- 

 shire, and named Stereognathus Ooliticus by Mr. E. Charlesworth. 

 This specimen, described in detail by Prof. Owen at the British As- 

 sociation Meeting in September last, indicated, in the author's opi- 

 nion, an animal allied to some extinct genera of even-toed pachy- 

 derms, viz. the Hyracotherium, Microtherium, and Hyopotamus of the 

 Tertiary deposits ; and he concluded therefore that the Stereognathus 

 was most probably a diminutive non-ruminant Artiodactyle of omni- 

 vorous habits. 



With regard to the zoological reasons for referring this peculiar 

 and ancient fossil to the type of animal form above alluded to, the 

 Professor entered at some length into the analysis of the mental pro- 

 cesses by which the palaeontologist aims at the restoration of an 

 unknown mammal from such a fragment as the fossil under notice. 

 Its mammalian character is decided by the two-fanged implantation 

 of the teeth, and its pachydermatous affinities are evidenced by the 

 peculiar sex-cuspid and cingulated molars. These zoological rela- 

 tions are determined from the knowledge that such structural pecu- 

 liarities obtain in certain known pachydermata. Morphology, there- 

 fore, or the study of form, rather than physiology, or the known 

 relation of organs to function, is the guide in this determination ; 

 but the Professor expressed his opinion that this example could not 

 be cited as showing that there is no physiological, comprehensible, 

 or rational law (in contradistinction to the morphological or empiri- 

 cal) which can be a guide in the determination of fossil remains. 

 He did not think that all such determinations rest upon the apj)lica- 

 tion of observed coincidences of structure, for which coincidences 

 no reason can be rendered ; for, although in many instances of this 

 law of correlation, as demonstrated by comparative anatomy, the 

 sufficient or physiological cause of them is not known ; yet, in 

 other instances, the application of the principle has been suc- 

 cessfully illustrated. The truth or fact (said Prof. Owen) of a phy- 

 siological knowledge of a correlated structure, and of the applica- 

 tion of that knowledge to palaeontology, is not affected or de- 

 stroyed by instances adduced from that much more extensive series 

 of correlated structures of which the physiological condition is not 

 yet known. 



