118 MAMMALIA. 



by the compression of powerful muscles, it is violently expelled 

 through a narrow opening on the top of the head. It is in this way 

 they produce those jets d'eau observed by navigators at so great a 

 distance. Their nostrils, continually bathed in salt water, could not 

 be lined with a membrane sufficiently delicate to enable them to de- 

 tect odours, and accordingly, they have none of those projecting 

 lamina? found in the nasal cavities of other animals; the olfactory 

 nerve is deficient in several, and if there be any which enjoy the 

 sense of smell, it must be in a very slight degree. Their larynx, of a 

 pyramidal form, penetrates into the posterior nares to receive air 

 and conduct it to the lungs, without compelling the animal to raise 

 its head and throat above the water for that purpose: there are no 

 salient laminae in the glottis, and the voice is reduced to a simple 

 lowing. They have no vestige "of hairs, but their whole body is 

 covered with a smooth skin, under which is that thick layer of blub- 

 ber abounding in oil, the principal object for which are they pursued. 



The stomach is divided into five and sometimes into seven distinct 

 sacs; instead of one single spleen, they have several, small and glo- 

 bular; those which are possessed of teeth, have them all conical and 

 alike; they do not chew their food, but swallow it rapidly. 



Two small bones, suspended in the flesh, are the only vestiges of 

 posterior extremities. 



Several have a vertical fin on the back, composed of a tendinous 

 substance, but unsupported by bone. Their eyes, flattened in front, 

 have a thick and solid sclerotica; the teguments of the tongue are 

 soft and smooth. 



They may be again divided into two small tribes: those in which 

 the head bears the usual proportion to the body, and those in which 

 it is immoderately large. The first comprehends the Dolphins and 

 the Narwhals. 



DELPHINTJS, Lin. 



The Dolphins have teeth in both jaws, all simple, and almost always conical. 

 They are the most carnivorous, and, in proportion to their size, the most cruel 

 of their order. 



DELFHINUS, Cuv. 



The Dolphins, properly so called, have a convex forehead, and the muz- 

 zle forming a kind of rostrum, or snout, in front of the head, more slender 

 than the rest. 



