

T.\. 



likewise very Urge, for the supply of tht vart 

 morn the tail" 



of nmsclm which 



Arterial Plextu in the Dolphins. Bmchet. 



With regard to the veins, Professor Owen points out that they are 

 remarkable not only for their great capacity, which Hunter noticed, 

 but also for their number and the immense plexuses which they form 

 in different parts of the body, and above all for the almost total 

 absence of valves. Tyson, he observes, haa given a figure of the 

 extensive venous plexus situated on the membrane investing the 

 psoas muscles, and these have recently occupied the attention of 

 Breachet and Von Boer. The inferior and superior vento cav:c are 

 not brought into communication by the vena azygos, as in other 

 Mammalia ; such veins in the usual situation in the chest would have 

 been subject to compression between the arterial plexuses and the 

 lungs. The vena; azygos are therefore represented by two venous 

 trunks situated in the interior of the vertebral canal, where they 

 receive the intercostal and lumbar veins, and finally communicate 

 with the superior cava by means of a short single large trunk, which 

 penetrates the parietes of the posterior and right side of the chest 

 Professor Owen concludes this interesting note to Hunter's 'Animal 

 Kconomy ' by clearing up the difficulty, which must have occurred 

 to most, of accounting for the fact of so enormous an animal as the 

 great whale being killed by such puny instruments as the harpoon 

 and lance. " The non-valvular structure of the veins in the Cefacra," 

 ays the Professor, " and the pressure of the sea-water at the depths 

 to which they retreat when harpooned, explain the profuse and 

 deadly hemorrhage which follows a wound that in other Mammalia 

 would be by no means fatal." 



Respiratory System. Phytophagous Cetaceans. Professor Owen 

 state! that the peculiar form, structure, and position of the lungs 

 have been so accurately described and figured by Raffles, Home, and 

 Kuppell, that he has only to observe the close agreement with these 

 accounts which the structure of the parts presented in the three 

 Dugongi dissected by him. Daubenton and Humboldt, he remarks, 

 describe and figure a precisely similar condition of the respiratory 

 apparatus in the Manatee. Htcllcr, ho adds, describes the same 

 extension cf the lungs in the Itylina, and compares it with the lungs 

 in the Bird, but without their fixation in the parietes of the chest, so 

 characteristic of that class. Professor Owen is of opinion that the 

 Chelouian reptiles perhaps offer a closer resemblance to the Herbivo- 

 ' 'iff n in this respect ; and he notices it as worthy of remark, 

 that the air-cells of the lungs are larger in the Dugong than in any 

 other mammals. In the Carnivorous Cetacea, the air-cells, he observes, 

 are remarkably minute, and the lungs more compactly shaped and 

 lodged in a shorter thorax. 



itinues Professor Owen, "as both the Herbivorous 

 and Carnivorous Crfntta do, under such peculiar circumstances a* 

 air-breathing animals constantly dwelling in an clement the access of 

 wbjah to the lungs would be immediately fnt.il it might bo supposed 

 that the mechanism of the larynx, or entry to thu air-passage, would 

 be similarly modified in all the species, in order to meet the contin- 

 gencies of their aquatic existence. But we can as little predicate a 

 community of organisation in the structure of this ]>nrt, as of the 

 circulating or digestive system in The Dugong 



and tho l>t>lphiu pn-x-nl, in fact, the two extremes in the Maniiui- 

 ferous class, in the development of the epiglottis, which in one of the 

 chief internal characteristics of that class. In the true Vclaer.a and the 



n particular, it in remarkable for its great length, ami iu 

 the Dugong it can hardly be said to exist at all." 



Professor Owen, after giving a minute and accurate account of the 

 larynx, thus proceeds : 



"Amongst the true Cefaeta, we have observed that it is those 

 which subsist on the lowest organised animal substance, as the 

 JMn-nulir, which approach the nearest to the I 

 having the additional complexity of tho ctccum ; and it is interesting 

 to find that the name affinity is manifested in th 

 larynx. The epiglottis and aryteuoid cartilages, for example, are 

 relatively shorter in the Baltrnoptera than in IM/Ji iui; and as Mr. 

 Hunter has observed, they are connected together by the membranes 

 of the larynx only at their base; and not wrapped togetl 

 surrounded by that membrane as far as the apices, an in the Dolphins. 

 In the lialtrnuptcra also, the apices of these cartilages are not expanded, 

 as in the Dolphins, but diminished to an obtuse extremity. These 

 points of resemblance to the condition of the larynx in the Dugong 

 and Manatee are carried still further in the Mysticete Whale, at 

 least in the foetus dissected by me, and in which both the epi 

 and arytenoid cartilages were relatively much shorter, and the 1 1 . 

 cartilage larger and more convex than in the Piked Whale (Bahenoptera). 

 The thyroid cartilage is however a single piece in both genera of 

 lialtenulir, though deeply notched above and below ; and the larynx 

 presents several interesting individual peculiarities, which however 

 the minute and accurate descriptions and illustrations of this organ, 

 in both the Baltfnoptera and HaUrntr, published by Professor O. 

 s.mdit'ort, preclude the necessity of further dwelling upon." 



The diaphragm, lungs, bronchi, and trachea present in the Koophn- 

 gous Cetaceans secondary modifications only, but important 

 are exhibited in the nostrils, which serve to conduct the air from the 

 atmosphere to the lungs. The necessity for the act of spouting seems 

 to have led to the obliteration of the organ of smelling. an<l 

 formation of a new organ especially destined to fulfil th 

 Although this organ has only been studied thoroughly in tho 

 Dolphins, the probability is, that the apparatus in all the Zoophagoua 

 Cetaceans is the same. 



If, says Baron Cuvier, we trace the oesophagus upwards, we find 

 that when it arrives opposite the pharynx it appears to divid. 

 two passages, one of which is continued onwards to the mouth, while 

 the other ascends to the nose. Mucous glands and fleshy fibres, which 

 constitute several muscles, surround tho lost-mentioned passage. 

 Some of these are longitudinal, and arise from the circumference of 

 the posterior orifice of the bony nostrils, aud descend along that 

 canal to the pharynx and its sides; the others, which are annular, 

 appear to be a continuation of the proper muscles of the ph 

 The larynx rises into this passage in a pyramidal form, and ths 

 annular fibres have the power of constricting it. Mucous fu" 

 which pour out their secretion by conspicuous excretory in 

 prevail in this port When the lining of the nasal passage haa reached 

 the vomer, it becomes of a peculiar texture, thin, smooth, aud black, 

 is apparently destitute of vessels and nerves, and very dry. A fleshy 

 valve closes the two bony nasal canals at the upper or e.v 

 orifice. It is formed of two semicircles attached to the anterior eil^e 

 of that orifice, which it shuts by the agency of a very strong n 

 lodged above the intermaxillary bones. To open it, there is a m 

 for some foreign body to press against it from below ; and when it 

 is closed, it debars all communication between the nasal passages and 

 tho cavities above them, which cavities are two large membranous 

 pouches formed by dark mucous skin, and very much wrinkled when 

 empty; but when distended, they become of an oval shape, whii-h in 

 the Porpesse is about as large as a common wine-glass. The 

 pouches lie "beneath the integument in front of the nostrils, and 

 communicate with an intermediate space immediately ; 

 nasal organs, whose external orifice is a transverse scniilnnar slit. 

 Strong fleshy fibres expand and cover the whole upper surface . 



ins, radiating from the entire circumference of the cranium, 

 uniting above the two pouches, and adapted for eompi 

 forcibly. Now we will suppose that the Cetacean has taken 

 mouth water which it wishes to eject : it first sets the tongue and 

 jaws in motion as if it were about to swallow the water ; but, shutting 

 its pharynx, it forces the water to ascend into the nasal p- 

 where the annular fibres above mentioned accelerate its progr. 

 it raises the valves and distends the membranous pouches 

 The water, when once in the pouches, can be there retained till the 

 animal wishes to spout. When that wish is present, the Cci 

 closes the valve, and so prevents the descent of tho water into the 

 nasal passagei, and forcibly compresses the pouches by means of tin' 

 muscular expansion which overspreads them. The water, comp, M ,! 

 then to escape by the narrow semilunar aperture, is projected to a 

 height which corresponds to the amount of tho pressure applied. 



In the case of the Spermaceti Whale.it appears that the 

 occupies about a seventh of its time in breathing; an I v. 

 after long intervals, an enormous column of air mu-t rush into the 

 lungs and aerate a vast quantity of blood for the n 

 by Banter, In ordinary mainiinl.*, man and the .pia Imp, 

 instance, respiration is momcntai : h air only 



w inhaled to oxygenate the bl 



Tho spout-hole is simple in the D,.lpl. 



