1002 



INSECTIVORA. 



former class are very numerous and of very 

 various form in the different genera, and the 

 Great diversity of number in the molar teeth 

 depends in most cases upon these, the true 

 molares being but three on each side both 

 above and below in all the genera, excepting in 

 Chrysochloris, in which they are f:|, in Eri- 

 naceus, in which they are *:$, and in Centenes 

 \:\. In Chrysochloris the true molares are 

 very curiously and beautifully formed : they 

 are much compressed from before backwards, 

 of a three-sided form, each of the angles ter- 

 minating in a sharp elevated point; thus, in 

 those of the upper jaw, there are two situated 

 externally and one internally, and in the lower 

 jaw one externally and two internally. The 

 whole of the true molares, in all the Insecti- 

 vora, are formed of three-sided prisms, either 

 single or double, and surmounted by acute 

 tubercles. 



The salivary glands are generally much de- 

 veloped in the Insectivora. In the hedgehog 

 the parotids are larger than the submaxillary ; 

 the sublingual are placed in two rows, of 

 which the larger is situate nearest to the lower 

 jaw. In the mole these glands are very large; 

 the parotids are of an oblong shape, and the 

 maxillary are formed of several rounded and 

 detached lobes. In Sorex the maxillary glands 

 are of larger size than the parotids, and the 

 latter are situated very low to accommodate 

 the oblique direction of the auditory canal. 



The form of the stomach in this Order of 

 animals is perfectly simple, and does not greatly 

 vary in the different genera. It is situated 

 transversely with regard to the axis of the body, 

 is somewhat elongated, and the two orifices are 

 distant from each other, as in many of the 

 Carnivora, and in the insectivorous bats. 

 The cardiac pouch is generally distinct and 

 rounded ; the pyloric extremity, on the con- 

 trary, is conical and perfectly even. In Erina- 

 ceus the cardiac point is considerable, the en- 

 trance to the oesophagus being at no great dis- 

 tance from the pylorus ; and the internal coat 

 forms numerous rugae and folds. This form of 

 the stomach and the existence of plicae must be 

 considered as indicating an aberration from the 

 insectivorous type, and a certain degree of ap- 

 titude for the digestion of vegetable matters, 

 and we find accordingly that this, with a slight 

 exception or two, is the only family of the 

 Insectivora which can exist upon any but the 

 most exclusive animal aliment. The mole, the 

 Chrysochloris, and all their congeners, are in 

 this latter case ; but the hedgehog, as is well 

 known, will readily eat various vegetable sub- 

 stances, and often digs under the common 

 plantain for the purpose of obtaining the roots, 

 of which it appeal's to be very fond. The sto- 

 mach varies a little in its form in the different 

 genera of the Soricida. In the great shrew of 

 India it is transverse, the pyloric portion coni- 

 cal, of moderate dimensions, the cardiac pouch 

 small and the two orifices distant; a form 

 which indicates an exclusive aptitude for insect 

 food ; but it would appear that the water-shrews 

 (Hydrosorex) must occasionally have recourse 

 to some kind of vegetable diet, as the pyloric 



portion is so much elongated as to resemble in 

 some degree that of the Pteropida or fruit- 

 eating Cheiroptera, exhibited in fig. 287, vol. i. 

 p. 600. In the mole the oesophagus enters at 

 about the middle of its anterior margin, and 

 the lesser curvature is nearly straight to the 

 pylorus. The membranes are extremely deli- 

 cate and almost transparent. The form is es- 

 sentially similar in Chrysochloris and in Con- 

 dytura. The stomach of Tupaia, according to 

 the Baron Cuvier, is of a globular form. 



The intestinal canal is upon the whole re- 

 markably short in the Insectivora. There are 

 some exceptions to this rule, but the only one 

 bearing upon a difference of aliment is that of 

 the hedgehog, which, as has been before ob- 

 served, lives partially upon vegetable matters. 

 In this animal it is, with regard to the length 

 of the body, as 6.6 to 1 . In Talpa and Centenes 

 this proportion is even exceeded, but it is com- 

 pensated for by the extreme narrowness of the 

 canal ; the diameter of which is to its length, 

 in the mole, as 1 to 82 ; whilst in the hedge- 

 hog it is as 1 to 58. In Sorex its length is to 

 its diameter only as about 3 to 1, or a little 

 more. There is no coecum known to exist in 

 any of the Insectivora. Cuvier queries whe- 

 ther Tupaia be not an exception, but this we 

 have at present no means of ascertaining. The 

 liver is in general fully developed in all its 

 parts; there are the principal lobe, to which 

 the gall-bladder is attached, with a notch 

 answering to the suspensory ligament, a right 

 and a left lobe, and two smaller lobes or /o- 

 buli, a right and a left. The whole of these 

 parts are generally found, but varying without 

 any known law, or any ascertained relation 

 to functional peculiarity. In the hedgehog 

 and in the mole the left lobule is composed 

 of two portions, a cardiac and a pyloric, as in 

 the Rodentia. In Tupaia, according to the state- 

 ment of Cuvier, the three portions into which 

 the liver is divided belong to the principal lobe; 

 there is no right or left lobe, and the right lo- 

 bule is also wanting. The gall-bladder is for 

 the most part of considerable size. In the 

 hedgehog its fundus appears beyond the free 

 margin of the liver, and is supported by a 

 process of falciform ligament. In the Tenrec, 

 on the contrary, it is as it were incrusted by 

 the substance of the right portion of the prin- 

 cipal lobe. 



IV. Nervous system. The form and propor- 

 tions of the brain in some of the Insectivora ex- 

 hibit a degree of developement not materially 

 superior to that of the higher Carnivora; whilst 

 others, and especially the mole, have the same 

 higher proportion which are found in the Chei- 

 roptera : thus in the hedgehog the volume of 

 the brain is to that of the body as 1 to 168; 

 whilst in the mole it is as 1 to 36. The pro- 

 portion of the cerebellum to the cerebrum in 

 the latter animal, however, indicates a consi- 

 derable developement of the sexual functions, 

 being as 1 to 4. Supposing the theories of 

 many modern physiologists to be correct, this 

 fact is in perfect accordance with the neces- 

 sities of the animal, whose means of obtaining 

 access to the opposite sex are extremely diffi- 



