CETACEA. 



581 



however, been studied with any detail in the 

 Dolphins, and its principal parts consist in 

 the larynx, which ascends as far as the pos- 

 terior nares; in the disposition of the mus- 

 cles of the pharynx, which have the power 

 of binding the anterior part of the respiratory 

 organ ; and in the membranous and fleshy bags 

 placed at the superior part of the nostrils. 



The orifice of the spouting hole, which is 

 simple in the Dolphins, is situated towards 

 the summit of the head (f,fig> 269); in the 

 Cachalots it is equally simple, and situated 

 at the superior extremity of the snout; and in 

 the Whales it is double, and opens towards 

 the summit of the head, as in the Dolphins, 

 under the form of a crescent, the convexity of 

 which is sometimes forward and sometimes 

 backward . 



In the Herbivorous Cetaceans, the orifice of 

 the nostrils is found, in the Manatee at the 

 anterior extremity, and in the Dugong at the 

 middle and upper part of the snout. 



[We here subjoin the detailed description of 

 the spouting apparatus of the Porpesse, from 

 the pen of Baron Cuvier. " If we trace the 

 oesophagus upwards, we find that when it 

 arrives opposite the pharynx (a, fig. 269), it 

 appears to divide into two passages, of which 

 one (6) is continued onwards to the mouth, 

 while the other (c) mounts to the nose: 

 this latter passage is surrounded with mucous 

 glands and fleshy fibres which constitute 

 several muscles. Some of these are longitu- 

 dinal, arising from the circumference of the 

 posterior orifice of the bony nostrils, and de- 

 scending along that canal to the pharynx and 

 its lateral parts; the others are annular and 

 seem to be a continuation of the proper mus- 

 cle of the pharynx ; as the larynx rises into 

 this passage in the form of an obelisk or py- 

 ramid, these annular fibres have the power of 

 grasping it by their contractions. 



" All this part is provided with mucous fol- 

 licles which pour out their secretion by con- 

 spicuous excretory orifices. The lining mem- 

 brane of the nasal passage having reached the 

 vomer (d\ assumes a peculiar texture; it be- 

 comes thin, smooth, and of a black colour, 

 is apparently destitute of vessels and nerves, 

 and is very dry. 



The two osseous nasal canals are closed at 

 the superior or external orifice by a fleshy 

 valve in the form of two semicircles, attached 

 to the anterior margin of that orifice, which it 

 closes by means of a very strong muscle lodged 

 above the intermaxillary bones. In order to 

 open it, some foreign body must press against it 

 from below. When this valve is closed, it cuts 

 off all communication between the nasal pas- 

 sages and the cavities above them. These ca- 

 vities are two large membranous pouches (e, e), 

 formed by a dark-coloured mucous skin, much 

 wrinkled when they are empty ; but assuming, 

 when distended, an oval figure, which, in the 

 Porpesse, equals the capacity of a wine-glass. 

 These two pouches are lodged beneath the 

 integument, in front of the nostrils ; they 

 communicate with an intermediate space im- 

 mediately above the nostrils, which open ex- 



ternally by a transverse semilunar slit. Very 

 strong fleshy fibres form an expansion, which 

 covers all the upper surface of this apparatus 

 these fibres radiate from the entire circum- 

 ference of the cranium to unite above the two 

 pouches, and are adapted to compress them 

 forcibly. Let us suppose the Cetacean has 

 taken into its mouth some water which it 

 wishes to eject : it moves its tongue and jaws as 

 if it were about to swallow it; but, closing its 

 pharynx, it forces the water to mount into the 

 nasal passages, where its progress is accelerated 

 by annular fibres, until it raises the valve and 

 distends the membranous pouches above. 

 Once in the pouches, the water can be re- 

 tained there until the animal wishes to spout. 

 For that purpose, it closes the valve to prevent 

 the descent of the water into the nasal passages, 

 and it forcibly compresses the pouches by 

 means of the muscular expansions which cover 

 them : compelled then to escape by the nar- 

 row crescentic aperture, it is projected to a 

 height corresponding to the force of the pres- 

 sure." 



Urinary organs. The Phytophagous Ceta- 

 ceans are not distinguished by a form and 

 structure of the kidney different from that in 

 the Zoophagous tribes ; for, although in the 

 Dugong the kidney has an uniform unbroken 

 external surface, yet in the genus Rytina, 

 according to Steller, that organ is subdivided 

 into a great number of lobules, as in the Seal 

 and Sea-Otter, and consequently resembles in 

 this respect the typical or true Cetacea. Hun- 

 ter makes the same statement with respect to 

 the Manatee.* 



In the Dugong the tubuli uriniferi terminate 

 by two lateral series of eleven mammillae in a 

 single elongated pelvis, from which the ureter 

 is continued. In the Porpesse and Whale 

 there is no common pelvis, but the ureter com- 

 mences by more than two hundred branches 

 from as many distinct lobes or renules, of the 

 aggregate of which the entire kidney is formed 

 (E,jig. 266). Each renule is of a conical figure, 

 having its base towards the circumference, and 

 its apex towards the centre of the kidney ; 

 it is composed of a cortical and medullary 

 substance, the latter terminating in a single 

 mammilla at the apex, where it is surrounded 

 by a long infundibulum, wide at its com- 

 mencement, where it embraces the base of the 

 mammilla, and thence becoming smaller, and 

 uniting with others to form the common ex- 

 cretory duct. 



Miiller found that each of the lobules of 

 the kidney in the foetus of the Dolphin con- 

 sisted principally of the convoluted uriniferous 

 ducts extending from the apex to the periphery 

 of the lobule, the intertwinings of the tubuli 

 being greatest in the cortical part (Jig. 270). 



It is a curious fact that the supra-renal gland 

 in the Porpesse presents a certain resemblance 

 to the kidney in its lobulated exterior ; but the 

 analogy extends no farther, for on making a 

 section of this part, it is seen to be composed 

 of the usual continuous compact substance.] 



* In the paper on Whales, p. 412. 



