

^ 









if 



* 









' 











.- 





,*f 







Ch. IX.] 



AT SUCCESSIVE GEOLOGICAL PEEIODS. 



161 



porary quadrupeds as yet obtained from the same rocks. (See 



%. 6.) 



Although the teeth differed in structure from those of any 



recent or fossil animal yet known, they are admitted by ana- 

 tomists to have more affinity to the higher or placental 

 division of the mammalia than any of the species previously 

 found at Stonesfield, or those yet procured from any rocks 

 older than the Tertiary. It is conjectured by Professor Owen 

 that it may have been a small, hoofed, herbivorous animal, but 

 he still regards this conclusion as very doubtful ; so far does 

 Stereognathus depart from any known type whether living or 

 extinct. 



When the Stonesfield oolite had continued for nearly 

 thirty years to be the only rock which had in any part of 

 the world afforded an example of a fossil mammifer anterior 



in 



mammifer, called Microlestes 

 Trias of Stuttgardt in 1847 * 



ras discovered in the Upper 

 Between that year and 1863 

 Somersetshire, and a stratum 



North 



plied us with the jaws and teeth of two or three species of 



diminutive marsupials. The 



mammalia as yet 

 i formations older 





Uppermost 



beck strata in Dorsetshire, where about fourteen species, 



met 



them 



oi the same sub-class, belonging to insectivora of low grade, t 

 It may, no doubt, be said that our acquaintance with the 

 purely freshwater strata of periods older than the Secondary 

 is very defective, and that we ought therefore to expect that 

 memorials of land animals in marine strata of Primary or Pa- 

 leozoic date would be very exceptional. There are regions at 

 present, in the Indian and Pacific Oceans, coextensive in area 

 with Europe and North America, where we might dredge the 

 bottom and draw up thousands of shells and corals, without 

 obtaining one bone of a land quadruped. Suppose our mari- 

 ners were to report, that, on sounding in the Indian Ocean 





* Elements, pp. 430-440. 

 VOL. I. 



f See Elements, p. 383 



M 





