COMI'AUATIVK ANATOMY. 



Hunterian Museum, have shown to belong to aa intermediate 

 type, shedding only one tooth (Fig. XIV., 2, 2), a fact which ha* 

 been previously overlooked by observers. 



Alimentary Canal. The mouth is separated from the upper 

 part of the gullet by a pendulous miuculo-membranous fold 

 called tho soft palate. This prevent* the food, during the act 

 of swallowing, from entering the back part of the nose. The 

 upper part of the gullet is called the pharynx. It is a muscular 

 bag common to both the food and air pusssgoa The opening 

 into the windpipe u protected by a movable leaf-like lid of 

 cartilage, which effectually closes it daring the passage of tho 

 food into tho gullet. The food is propelled along the gullet by 

 the successive action of the muscular fibre* of which the tube 



is mainly com- 

 posed. This act 

 is beyond the con- 

 trol of the will. 

 In many of the 



. I :. Ill uii'l IV. 1,1); and the root 



witli a material which id named cortical unbalance, or cement 

 111. ami 1\ .-.-lami'l, when examined nml.-r 



Hi.- i:,i.-:..-.'opo, appears like a number of Mix-Hided prisms 

 closely pressed against each other, ami directed perpendicularly 

 towards the surface of tho tooth (Fig. V.). Tho dentine is 

 composed of delicate branching tubes, which run from the 



i cavity (Figs. III. and IV., 4, 4) toward < oof the 



In tho u halo tho teeth are represented by largo flexible 



in the upper jaw, called whalebone (Figs. VI. and VII.). In 

 man, ami tii. In ,'hor apes, monkeys, etc., there arc in each half of 

 'I tooth, chisel-shaped, named incisors, or out- 

 1., 1) ; a more pointed one called the canine, or 

 dog-tooth, for 

 biting, holding, 

 ami t.'arii. 

 11.,:.'); iv.o some- 

 what flattened at 

 the top, with sin- 

 gle fangs, called 



<>r promo- 

 lar.s (Fi,-. II., o) ; 

 and three situ- 

 ated behind all 

 tho rest, the 

 true molars or 

 grinders (Fig. II., 

 H. To express 

 tho number of 

 teeth in a simple 

 manner, the fol- 

 lowing table is 

 used by natura- 

 lists, and called 

 tho dental for- 

 mula : 



. 8^ ri 



U L' J ; ' 1-1 J 



2-2 3-3 



P- TO - .,.., . "! .. .., 



The 

 toeth 



small in the in- 

 aeotivora, strong 

 and large in the 

 hcrbivora and ro- 

 dente. The ca- 

 nines aro large in 

 the carnivorous 

 and some other 

 animals. Figs. 

 VIII., IX., X., 



and XI. show ex- MAMMALIA. XII. & XIII. STOMACH, AND SECTION OF STOMACH, OF SHEEP (AFTER MILNE-EDWARDS). 

 XIV. Snowix.; DENTITION OF A MARSUPIAL (AFTER FLOWER). XV. SKELETON OF A CAMEL. 



incisor 

 are very 



ample.* of the 

 teeth in the car- 

 nivorous, insecti- 

 vorous, herbivo- 

 rous, and frugi- 

 vorous animals. 

 The narwhal has 

 only two tooth. 

 The elephant has six viz., an entire molar on each side of XII. and XIII.). 



Befs. to Nos. in Figs. XII. and XIII. 1, 1, gullet ; 2, 2. third stomach ; 3, 3, second stomach ; 4, 4, 

 paunch ; 5, fourth stomach ; 6, 6, pylorus and intestine ; 7, sesophogeal groove. XIV. 1, 1, per- 

 manent, and 2,2, deciduous teeth. XV. 1, blade-bone or scapula; 2, humerus; 3, ulna or cubi- 

 tus ; 4, carpus; 5, metacarpus ; 6, phalanges; 7, femur; 8, tibia ; 9, tarsus; 10, metatarsus ; 11, 

 phalanges ; 12, cervical vertebra; ; 13, dorsal ditto ; 14, lumbar ditto ; 15, sacrum or sacral ditto; 

 16, caudal or ox-tail ditto ; 17, ribs. 



both jaws, together with two tnsks of the upper jaw. In 

 rodents the toeth vary from 12 to 28. In ruminants, apes of 

 the Old World, and commonly throughout the mammalia, there 

 are 32, tho typical number, however, being 44 (Owen). The 

 eacholot (spermaceti whale) has more than 60 (which are con- 

 fined to the lower jaw) ; and the dolphin 100 to 190. 



Animals ore said to be monophyodonts that generate a single 

 set of teeth, and diphyodonts that generate two seta of teeth. 



stomach is a sim- 

 ple membranoua 

 bag, stretched 

 transversely 

 across the upper 

 part of tho ab- 

 dominal cavity, 

 and carved some- 

 what upon itself. 

 The upper curve 

 is smaller than 

 the lower. The 

 point where the 

 food enters is 

 called the 0so- 

 phageal opening, 

 and that where it 

 leaves the sto- 

 mach the pyloric 

 (from the Greek, 

 signifying a gate- 

 keeper), because 

 it is constricted 

 by an aggrega- 

 tion of the mus- 

 cular fibres of the 

 stomach into & 

 circular ring, 

 which effectually 

 guards tho aper- 

 ture until the 

 food is suffi- 

 ciently digested 

 to permit of its 

 passage into the 

 intestine. In ru- 

 minants the sto- 

 mach is much 

 more compli- 

 cated,, being di- 

 vided into a. 

 number of com- 

 partments (Figs. 

 The first stomach is called the paunch 



(4), the second the king's hood, or honey-combed stomach 

 (3), from being arranged in folds or cells similar to a honey- 

 comb ; tho third, or many plies (2), from its inner surface 

 being increased by a number of longitudinal folds ; the fourth, 

 or rennet (5), named from its property of curdling milk. The 

 ruminant swallows its herbaceous food partially masticated. It 

 descends into the first stomach, or paunch, which corresponds to 

 the crop of birds. When at leisure, the animal regurgitates the 



To tho first belong the monotremata (ornithorynchus and | food to the mouth. A part is passed into the second stomach, 



echidna), edentata* (sloths, etc.), and cetacea (whales). To the 

 second all the rest, except the marsupials, which the recent 

 researches of Mr. Flower, the present able conservator of the 



* Edentata ( and den*), without teeth. In many of the species 

 the teeth are entirely absent ; in others only partially so. 



and there formed into a smooth, moistened mass, and then pro- 

 jected into tho mouth, where it is now properly masticated, and 

 again swallowed. This time the morsel passes into the third 

 stomach, and, spreading over its longitudinal folds, is pre- 

 pared for admission into the fourth or true digestive stomach, 

 and thence into tho small intestine. In the camel and 



