996 



INSECTIVORA. 



genus the orbit is therefore circumscribed by 

 being closed posteriorly by the union of the 

 post-orbitar processes of the frontal and jugal 

 bones ; in all the other genera the orbit and the 

 temporal fossa are confounded in one cavity, 

 without the trace of any attempt at forming a 

 division between them. This peculiarity in the 

 genus Tupaia shews a marked tendency to- 

 wards the insectivorous Quadrumana. 



The bones of the face are very early united 

 in the Talpida and the Sorieida. In the 

 genus Centenes there is no jugal bone. There 

 is therefore no zygomatic arch, notwithstanding 

 the masseter muscle is of great size. This is 

 attached by a single tendon to a sort of tu- 

 bercle, which represents the zygomatic process 

 of the maxillary bone. In Tupaia the inter- 

 maxillary bones are very large, and their 

 suture descends vertically, nearly half way be- 

 tween the nares and the orbits. The Shrews, 

 like Centenes, have no malar bone, and the 

 zygomatic process of the maxillary is even less 

 conspicuous than in the former genus. Most 

 of the subterranean forms have at the extremity 

 of the muzzle, that is to say, around the open- 

 ing of the nares, a small rim or border, which 

 is especially conspicuous in the Chrygpchloris, 

 for the attachment of the large and moveable 

 cartilages of the nose, so important to these 

 animals in turning aside the earth as they make 

 their way through the ground, as well as in 

 seizing the worms and insects on which they 

 feed. 



The proportions of the spine vary greatly in 

 the different families of Insectivora, as may be 

 anticipated from the great difference in their 

 habits. On this subject it may not be useless 

 to subjoin the following table of the numbers 

 of the separate classes of vertebrae, which is 

 taken from the last edition of the Lecons d'Ana- 

 tomie Comparee of Cuvier : 



It is worthy of remark, in taking a compara- 

 tive glance at this list, that the length of the 

 tail in the different species is in exact accord- 

 ance with their habits, as far at least as we are 

 acquainted with them. Thus, in Tupaia, we 



observe a tail as long as that of a squirrel, and 

 obviously for the same object, that of balanc- 

 ing the animal when taking leaps from one 

 branch to another ; and in the Water-shrew the 

 tail is lengthened to assist in swimming, for 

 which purpose it is also fringed on each side 

 with stiff hairs. Of the habits of the Condy- 

 tura* we know little, and of that little nothing 

 which accounts for the considerable proportion 

 of the tail. 



Of the form of the different vertebrae in the 

 various groups of the Insectivora, little need 

 be said, as there are few circumstances con- 

 nected with these bones which bear materially 

 upon any physiological point. It may be ob- 

 served, however, that in the Talpida and the 

 Soricidtf the cervical vertebrae form large rings, 

 have strong transverse processes, and, except- 

 ing the second, do not possess any spinous 

 processes. In the Erinaceada, and particu- 

 larly in the Tenrec (Centenes) the transverse 

 processes are particularly large, and the rings 

 smaller than in the former families. The spi- 

 nous processes are also wanting in the dorsal 

 vertebrae of the mole. 



The sternum offers some peculiarities 

 worthy of notice. In the mole the first ster- 

 nal bone is very large and compressed. To its 

 anterior pointed extremity the thick short 

 clavicles are attached, and further back to the 

 same bone, the first rib is articulated ; to the 

 second bone is fixed the second rib, and there 

 succeed to these three elongated bones of the 

 ordinary form, to each of which two pairs of 

 ribs are articulated ; then a small bone, to which 

 one pair of ribs is fixed, and then the xiphoid 

 bone, which is long and narrow. 



In the Chrysochloris the first bone of the 

 sternum is equally compressed but less elevated ; 

 and the anterior half is furnished on the up- 

 per part with two small aliform processes, 

 which are concave, and support the first two 

 ribs, which are extremely broad; the long 

 slender clavicles are attached at its anterior 

 point; and then follow seven other oblong 

 pieces, and an elongated xiphoid bone, which 

 bears at its posterior extremity a semilunar car- 

 tilaginous dilatation. 



The ribs in the mole and its congeners are 

 nearly all of the same length, giving that pe- 

 culiar cylindrical form to the body which cha- 

 racterises these animals, and which is so essen- 

 tial to their habits ; and in the Chrysochloris the 

 first rib is very much broader than the others. 



But it is in the bones constituting the anterior 

 extremities, that the most remarkable and in- 

 teresting peculiarities exist in some of the 

 families of this group. In the mole especially, 

 the anterior extremity (Jig- 442) exhibits one of 

 the most extraordinary modifications to be found 

 in the whole of the Mammifera. The clavicle 

 is fully developed in the whole of the Insec- 

 tivora. In the mole (b) it offers the most 



* From the name condyiura, given to this genus 

 by Illiger, it might be inferred that the tail is 

 furnished with knotty tuberosities ; this, however, 

 is only seen in dried specimens, which doubtless 

 furnished to Illiger the characters of the genus, 

 and suggested its name. 



