297 



PHOCID.E. 



PHOCID^E 



its internal tuberosity and of its deltoid crest; its lower pulley ia 

 hollowed by an obtuse gorge and divided into two parts one external 

 and wider, convex in two directions, for the head of the radius ; one 

 internal and narrower, for the cubit Both the P. ritulina and the 

 P. mitrata have the internal condyle pierced with a hole for the 

 cubital artery, but this hole is wanting in P. Monachiis and Otaria. 

 The upper head of the radius is rounded and has a simple concavity, 

 is short and very much compressed, and dilated vertically for its lower 

 two- thirds. 



The ulna or cubit is very much compressed on its upper part, 

 where the olecranon is much higher than it is long, and gives off a 

 pointed apophysis towards the lower part. The hand of the Seal, 

 being principally destined for swimming, is cut obliquely, so that the 

 thumb forma its point and its most powerful edge ; it has nevertheless 

 only two phalanges as in ordinary, but its metacarpal bone and its two 

 phalanges make it longer and stouter than the other finders. The 

 articulations of the phalanges are not well marked. The ungueal 

 phalanges of the Seals have one remarkable conformation, namely, 

 that the point which is sheathed in the claw cornea out, in some 

 degree, from the upper surface of the bone, and the rest of the bone 

 forms, as it were, two little wings. In the Otaricf, which have no 

 claws before, the ungueal phalanx is simply depressed and obtuse. 



The pelvis of the Seals, and especially the ossa ilii, are reduced to 

 very small dimensions. 



Of all the bones of the Seals the femur is the most extraordinary 

 for its shortness ; it is hardly longer than it is wide : in the lower part 

 especially it is flattened and dilated laterally, having a crest at its 

 internal border and a tuberosity on its external border. Its rotular 

 pulley is flat and nearly vertical. The articular surfaces for the tibia 

 are wider than they are long. 



The tibia is twice and a half as long as the femur, and is rather 

 stout, especially above, where in age it becomes soldered with the 

 fibula, but always remains distinct from it below. The interval 

 between them is rather wide. The fibula itself is rather stout. 



The astragalus of the Seals is very extraordinary ; for instead of 

 being more or less hollow in the middle of its articular surface, it 

 offers to the leg a convex pulley formed of two faces, which together 

 form a projecting angle like a roof, and one of which responds to the 

 tibia, and the other (the largest) to the fibula. This bone has not only 

 an apopbysis forward for the scaphoid bone, but has another back- 

 ward, terminated by a tuberosity and forming a sort of internal heel, 

 so that if looked at separate from the rest it might be taken for the 

 os calcis. Upon this tuberosity of the astragalus the long flexor of 

 the toes passes in a groove. 



The great and little toes are larger than they are long, and the 

 middle toe is the shortest, so as to give the hind foot a forked appear- 

 ance; the great toe nevertheless has but two phalanges. All the 

 articulations of these phalanges are as little developed as in the fore 

 feet. 



The ribs are angular rather than flat, and slight when compared 

 with those of the Dugongs. In the Seals there are ten whose carti- 

 lages are attached immediately to the sternum, and nine only in 

 Otaria. The ninth rib in the Seals is attached to the side of the 

 eighth bone of the sternum, and the tenth, as ordinarily, to the interval 

 of the eighth and ninth : this last is cylindrical, longer than the others, 

 and terminated by a cartilaginous dilatation. The others are depressed. 

 In front of the first and last pairs of ribs there is in the Seals a pointed 

 cartilaginous prominence, which in Otaria is ossified, and makes part 

 of the body with the first bone. (' Ossemens Fossiles.') 



Skeleton of Seal (Phoca ritulina]. 



In these Pinnigrade Perce the whole form is adapted for progres- 

 sion in water. Instead of the lengthened anterior extremities and 

 phalanges of the bats, framed to support a wing for their passage 

 through the air, we have all the bones of those extremities in the Seal 

 short and compact, in order to support the finlike arm and deteriorated 

 hand. We have the conical shape of the body and the extremely 

 narrow pelvis, to favour that shape so as to produce the least resist- 

 ance in passing through the water, with the short femur and posterior 

 extremities directed backwards. In the skull we have the defective 

 orbit observable in all the Carnivora, by which space it gained for 

 the zygomatic arch and the highly developed temporal muscle. The 

 broad development of the transverse processes of the atlas is here also 

 remarkable, and the cervical vertebra are framed for extensive motion. 



The spinotis processes of the vertebras have a posterior deflection so 

 as to act in unison for the necessary aquatic progression. The clavicle 

 is absent, as in the Feres generally, but the scapula ia broad. The 

 number of carpal bones is the same as in the lion, and the number of 

 ribs may be stated at fifteen pairs. 



Considerable differences exist in the crania of the various Phocidce, 

 well justifying, with other discrepancies of structure, the division of 

 the family into several genera. 



The Stomach of the Seal (Phoca vitulina) differs from the ordinary 

 form : the oesophagus enters directly at the left extremity, so that 

 there is no blind sac in the stomach. 



The seals have the power of opening or closing their nostrils at 

 pleasure, and the interval between their respirations is very long. This 

 may be observed in those which are kept in confinement ; and the 

 closing appears to be effected by sphincter-like muscles acting upon 

 valvules which shut the aperture most effectually. Such a provision 

 is absolutely necessary for animals that pass so much of their life in 

 the water and take their food there : for ordinarily the seal eats in 

 the sea, though it can eat upon land, as those who have seen the 

 individual fed, in the Gardens of the Zoological Society in the Regent's 

 Park, well know. The breathing is not only slow, it is also irregular. 

 After opening the nostrils and making a strong expiration, the animal 

 inspires a large quantity of air, and closes the nostrils. In the intervals 

 of this infrequent respiration, it is evident, from the free motion of 

 the ribs and the general deportment of the animal, that the lungs 

 receive their regular supply of air. In a state of nature a quarter of 

 an hour and as much as twenty-five minutes have been known to 

 elapse between their descent from the surface and their ascent thither 

 for the purpose of obtaining a fresh supply ; and in confinement they 

 have been observed to remain asleep with the head under water for 

 an hour at a time, and consequently without breathing during that 

 period. To account for this power physiologists were of opinion that 

 the foramen ovale remained unclosed in these animals, and that thus 

 the sanguiferous circle was not interrupted during the time of their 

 stay under water ; but Cuvier and Lawrence found it closed in the 

 seals dissected by them, and we must look to some other conforma- 

 tion for the endowment of this faculty. Thus Cuvier states that 

 there is a great venous sinus in their liver, which assists them in their 

 divings by rendering their respiration less dependent upon the circu- 

 lation ; and Mr. Houston has pointed out other venous reservoirs in 

 the neighbouring parts. These provisions seem to be quite different 

 from the great arterial plexus first pointed out by John Hunter in the 

 Cetacece ; for in the Seals the blood appears to be laid up not in a net- 

 work of vessels, but, so to speak, in wide canals. The term veineux 

 is certainly used by Cuvier, and a reservoir of arterial blood would, 

 reasoning from analogy, be required for the purpose of keeping up 

 healthy life during submersion ; but there can be little or no doubt 

 that these reservoirs are intimately connected with the power of 

 remaining long beneath the water, though, as yet, the mode of opera- 

 tion U not satisfactorily made out, as it is in the Whales. The last- 

 mentioned author states that their blood is very abundant and very 

 black. 



The Brain of the Seals is well developed, and the degree of sagacity 

 and attachment shown in domestication (for they are very easily 

 tamed and taught to perform tricks) is evidence of superior intelligence. 

 This has been long ago observed :" Accipiunt disciplinam," says 

 Pliny (' Nat. Hist.,' ix. 13), " voceque pariter et visu populum salutant, 

 incondite fremitu : nomine vocati respondent." F. Cuvier too saw 

 one display much intelligence ; he performed what he was ordered to 

 do. When desired to raise himself erect on his hind legs and to take 

 a staff in his flippers, like a sentinel, he obeyed the word of command : 

 he would lie down on his right side or on his left, according to order, 

 and tumole head over heels when directed to do so. He gave a paw 

 when requested, like a dog, and protruded his lips for a kiss. This 

 animal appeared to be very fond of its master. 



Blumenbach remarks that it has long been known that the sclerotic 

 coat in several mammals is, as in the human subject, not of equal 

 strength throughout; but that its posterior part is much thicker 

 than its anterior. It has also been conjectured that this structure 

 might influence what are termed the internal changes of the eye, by 

 which the form of the eyeball, and consequently the length of its axis 

 and the relative situation of the lens are adjusted according to the 

 proximity or distance of the object, or indeed with reference to any 

 >ther relations. Blumenbach remarks that he flatters himself that he 

 ias ascertained the truth of this conjecture by discovering the admir- 

 able structure of this coat in warm-blooded animals, which have not 

 only the power of seeing at various distances, but also in two media 

 of such different density as air and water. In the eye of the Green- 

 and Seal, where he first noticed the fact, the cornea was thin and 

 yielding; the anterior segment of the sclerotica, or that which is 

 mmediately behind the latter membrane, was thick and firm ; its 

 middle circle thin and flexible ; and lastly, the posterior portion very 

 thick, almost cartilaginoua. The whole eyeball was surrounded with 

 very strong muscles; and it may be easily understood how their notion, 

 uodified according to circumstances, produces the requisite chauges; 

 low the axis of the eye is shortened when the animal sees in the air, 

 >y bringing the lens nearer to the back of the globe, iu order to 

 bviate the strong refraction which the rays of light undergo in 



