Recent geological Discoveries.. 191 



era solitudes jto ' eschew tke lowland plains and thickets, and 

 haunt the bare bleak hill-sides, which, exposed and barren though 

 they are, suit better his short limbs, and enable him from a van- 

 tage gromid to resist his enemies. His form of limb, too, appears 

 to be especially adapted to climbing the precipitous heights which 

 are his favorite resorts. 



Passing over some new views of the sub-divisions of the tertiary 

 series, and other items of tertiary geology, we come to the an- 

 nouncement that in the space of a few months, remains of seven 

 or eight genera of mammals have been discovered in the Purbeck 

 or Upper Oolite strata of England, and this in one small bed five 

 inches thick, and in a very few square yards of that bed. 



Hitherto the whole secondary series had yielded since 1818, 

 when the first mammalian jaw was found in the Stonesfield slate, 

 onlv six species of small mammals. Thirteen, or twice as many 

 species have all at once appeared from this little bed of the Pur- 

 beck. The fact is significant as to the danger of deciding on 

 what was not in by-gone periods. Jl^o rocks have been better 

 explored than the secondary rocks of Western Europe. They 

 have yielded great numbers of the bones of reptiles and fishes, 

 yet in 36 years only six small mammals had been found. The 

 Purbeck series itself had been carefully examined by the late 

 Edward Forbes, and by the Geological Survey, as well as frequent- 

 ly ransacked by collectors, and had afforded no trace of mammals ; 

 and now all at once it proves most prolific of them. 



But what manner of mammals are these ancient creatures ? 

 not huge pachyderms, lilve those of the tertiary era which succeed- 

 ed them, but small creatures, none of them larger than the 

 hedge hog. The greater part are insectivorous, or at least preys 

 on small animals ; two species herbivayous, with, a peculiar ro- 

 dent dentition, resembling that of the Kaijgaroo-rat of Australia. 

 Tl^e greater number of these little animals %ere probably marsu- 

 pial or pouched, like. the prevailing quadrupetkin Australia, but 

 some others have apparently been placental, like our ordinary 

 mammats. Among the latter is a little creature which, according 

 to Prof. Owen, must have been a diminutive example of that type 

 of hoofed animals to which the hog and peccary belong. 



One of the results-^-and hot the least curious, of the Purbeck 

 discoveries, is, that the little Mici'olestes, of the German Trias, the^ 

 dtligst known mammal, must have resembled the two Purbeck 

 specie? of-i' Plagiaulax," which are related to the Kangaroo-rat. 



