56 THORACIC AND LUMBAR VERTEBRAE. [CHAP. 



varies much in the different genera, from 1 8 (13 thoracic and 

 5 lumbar) in Tupaia, 19 (13 and 6) in Talpa and most 

 Soricidcz, 19 (14 and 5) in Gahopithecus, 21 (15 and 6) in 

 Erinaceus, 22 (19 and 3) in Chrysochloris, to 24 (19 and 5) 

 in Centetes. 



There are also great differences- in the development of the 

 processes of the vertebrae, which appear to accord with the 

 diversities in the habits and movements of the animal. The 

 transverse processes of the lumber vertebras are very short 

 in the comparatively slow-moving, running, or burrowing 

 Hedgehogs (Erinaceus), Shrews (So rex) and Moles (Talpa), 

 but they are very long, broad, and inclined downwards in the 

 jumping Macroscelides and Rhynchocyon, where the lumbar 

 muscles are greatly developed and the hinder extremities 

 disproportionately large. 



In the Mole, there are distinct, small, oval, flat ossicles on 

 the under-surfaces of the interspaces between the lumbar 

 vertebras. Similar ossicles, but in a more rudimentary con- 

 dition, are occasionally found in the same situation in some 

 other Insectivora, as the Hedgehog, but not in any other 

 Mammals. 



The usual number of thoracic and lumbar vertebrae in the 

 CHIROPTERA is 17 or 18, of which from n to 14 may bear 

 movable ribs. The transverse processes of the lumbar 

 vertebras are almost obsolete, as are also the spinous pro- 

 cesses throughout the series. 



Among the RODENTIA, the most prevalent number is 19 ; 

 but it rises as high as 23 (16 and 7) in Capromys, and even 

 as 25 (17 and 8) in Loncheres. 



The characters of the vertebras vary much in the different 

 genera, as among the Insectivora. In the Hares (genus 

 Lepus) the anterior thoracic vertebrae have long slender 

 spinous processes; the lumbar vertebras (see Fig. 3, p. 18) 



