MAMMALIA. 



frequently wanting ; it always lies upon the external wall of tli 

 nasal cavity, and where there is an antrum, it is contained within 

 the cavity, and its duct terminates at the anterior extremity of the 

 inferior meatus. In animals provided with a snout, the nasal 

 cartilages are lengthened out to a tube, which is covered with mus- 

 cles that move it in many directions. Frequently, as in the Hog 

 and the Mole, there lies near to the root and in the substance of 

 the snout a peculiar bone. . Internally the snout is divided into a 

 double tube, and the whole structure is particularly remarkable in 

 the Elephant, where it forms that highly developed organ of touch 

 and prehension, the proboscis, which, is lined internally with a dry 

 epithelium ; its two tubes are contracted in the vicinity of the inter- 

 maxillary bones, by which the ingress of water when sucked up is 

 prevented ; it consists of very numerous longitudinally arranged 

 muscular bundles, with tendinous contracted portions, which, when 

 they act, shorten the proboscis, while their antagonists are trans- 

 verse or oblique bundles, imbedded in a net-work of adipose tissue. 

 In all, there are reckoned about 30,000 to 40,000 bundles. Special 

 elevators and depressors arise from the frontal and superior max- 

 illary bones. In the Mole, there lie upon each side of the- snout 

 four muscles, which arise from the upper jaw, and are attached by 

 their tendons to the nasal tube, like ropes to a mast. In many 

 Cheiroptera, as Rhinolophus, Phyllostoma, peculiar appendages, 

 partly cartilaginous, partly membranous, and of very singular forms, 

 are developed upon the nose. Diving animals have occasionally 

 valves by which the nasal passages can be closed internally, as in 

 the Ornithorynchus, where the small round nasal openings lie at 

 the base of the snout, The seals have an annular sphincter muscle 

 round the nostrils. In the male of Phoca cristata, the Cystophora 

 borealis, the nose is not developed into a snout, but presents itself 

 as a large musculo-membranous bag, into which the animal can 

 introduce air. 



The nose of the Cetacea departs from the type of the rest of the 

 Mammalia, and is developed into the blowing canal, while it takes 

 a perpendicular direction, and terminates superiorly in front of the 

 fore-head, as the blow-hole. The bony nasal cavity is therefore 

 extremely simple. It consists, for example, in the Dolphin and in 

 the Narwhal, of a simple smooth bony canal upon either side, 

 without sinuses or turbinated bones. The nasal or spouting 

 opening is single in the Spermaceti Whale, the Narwhal and the 

 Dolphin; the Whales (Balama) have two nasal openings, and 



