30 



GEOLOGY. 



ORDER V. — RODENTIA (Gnawing Animals). 



The Rodents (Table-case No. 24, North side), represented by 

 the Hares, Rabbits, Porcupines, Beavers, Rats, Mice, Dormice, 

 Squirrels, and Marmots — are characterized by having two curved 

 chisel-shaped incisors, or cutting, teeth in each jaw, widely separated 

 from the molar or grinding teeth. 



There are usually two or three incisor teeth in the upper and tw& 

 in the lower jaw (but sometimes there are four upper incisors). 

 These animals have no canine teeth, but they generally have four 

 molars on each side, above and below. 



The oldest Rodent known is found fossil in the Eocene Tertiary 

 formation ; but such animals abound at the present day. Remains of 

 the hare (Lepus) are found fossil in both N. and S. America, and also 

 in Europe. The Lagomys, or tailless hare, and the Marmot (Sper- 

 mophilus), characterize some of the Post-Glacial deposits in Britain. 

 The latter occurs at Erith in the Thames Valley. 



The Beaver is not only widely-spread at present, but its fossil 

 remains prove it to have had an equally wide distribution in the past. 

 It was once abundant in this country, as, for instance, in the valley 

 of the Lea, near London, and in the Cambridgeshire fens. It is 

 still found living in some of the rivers of Russia, and also in those of 

 North America. A far larger species of beaver, called Trogontherium, 

 once inhabited Norfolk, where its remains have been found in the 

 Cromer forest-bed. A still more gigantic form, the Castoroides 

 Ohioensis, is represented by a cast of the skull and lower jaw, from 

 the Post-Tertiary of North America. A gigantic dormouse (Myoxm 

 melitensis) has been found in the Post-Pliocene of Malta. 



Near Table-case 24, in Wall-case No. 23, are placed the skull and 

 lower jaw and some limb-bones of a colossal rodent-like animal, 

 named Toxodon, probably larger than a horse, but having true Rodent 

 teeth in its jaws. This remarkable fossil was obtained from the 

 Newer Tertiary deposits of Buenos Ayres, and, with another aberrant 

 form of Rodent, also from S. America, named Typotherium (see 

 Table-case No. 24), proves the enormous sizes to which some of these 

 extinct gnawing animals must have attained. 



ORDER VI. — CARNIVORA (Flesh-eating Animals). 



In the second Table-case (South side) are the remains of a large 

 number of carnivorous animals, chiefly from caves, representing 

 the Hvaena and Wolf, both ancient denizens of this Island ; with 

 the Fox, Dog, Badger, Glutton, Otter, Weasel, and many other allied 

 f orms — mostly represented by skulls and lower jaws. 



In Wall-case 1, and in Table-case 2, are placed the skulls, lower 

 jaws, teeth, and bones of the " great sabre-toothed tiger " (Machai- 

 rodus latidens), remarkable for the enormous development of its 



