124 



PHOCID.E. MAMMALIA. PHOCID.TJ. 



ORDER VI. PINNIPEDIA. 



THIS order of amphibious mammals, though, for con- 

 venience, here treated as a distinct group, cannot be 

 regarded as zoologically equivalent to any of the fore- 

 going ordinal divisions, inasmuch as it only represents 

 a peculiar section of the Carnivora, properly so called. 

 In accordance, therefore, with the system indicated at 

 the commencement of this work, the Pinnipeds or Seals 

 are here considered separately. The most marked and 

 obvious peculiarity in their organization, consists in 

 the conversion of the Kmbs into paddles or swim- 

 ming feet the modifications of structure by which this 

 change is brought about being best understood by 

 an examination of the skeleton (Plate 34, fig. 114). 

 Bearing in mind what we have already pointed 

 out respecting the osteology of the typical carnivor, it 

 will be noticed that the several skeletal elements of 

 the seal are more or less attenuated, compressed, and 

 shortened, according to circumstances. Thus, instead 

 of the broad massive skull, we have a rather elongated 

 cranium, associated with a movable spine, which is 

 even more flexible than that of ordinary cats. The 

 bones of the pelvis are particularly slender, and but 

 feebly developed, while the shoulder-blades are, on the 

 other hand, remarkably broad. There are no clavicles. 

 The homologous arm and thigh bones, that is, the 

 humeri and femora, are much shortened. The bones 

 of the fore-arm are considerably flattened ; and, in the 

 conformation of the hand, the adaptation of the limb 

 for natatory purposes is eminently significant. It will 

 be observed that the phalanges are drawn out, as it 

 were ; and; diverging from one another, like the spokes 

 of a wheel, they form mutually-resisting supports for 

 the interdigital webs. The hind paddles, with their 

 membranous expansions, are similarly constructed, 

 stretching out posteriorly in a horizontal direction. 

 Ah 1 the feet are pentadactylous, the toes of the anterior 

 extremity becoming, one after another, shorter from the 

 thumb outwards. The outer and innermost toes of 

 the hind feet are the most xtecsively developed. The 

 forward movements of the body upon land are pro- 

 duced by a rapid succession of short shuffling or 

 wriggling leaps, entirely due to the contraction of the 

 muscles of the trunk, and altogether independent of 

 the limbs, the latter only being employed in clambering 

 up the sides of projecting rocks. Generally speaking, 

 the bones are light and spongy in texture; and this 

 circumstance when taken in connection with the boat- 

 like form of the body, which terminates posteriorly in 

 a short and conical tail, the oar-like limbs, the smooth 

 adpressed fur, together with the flexible spine and 

 powerful muscles satisfactorily demonstrates how 

 much care has been taken to render these creatures 

 swift, easy, and vigorous swimmers. 



FAMILY I. PHOCIDJE. 



The true Seals have been divided into four sub- 

 families or minor groups, but their differentiating 

 characters are scarcely sufficient to warrant such an 



arrangement. The teeth are usually thirty- four in num- 

 ber, of which there may be reckoned six or only four 

 incisors above, and four or two below, together with 

 four canines, and twenty or twenty-two molars; all 

 having the crowns armed with trenchant conical points. 

 The tongue is smooth and bifid at the tip ; the stomach 

 is simple, the intestinal canal being comparatively long. 

 In connection with the liver, the posterior vena cava 

 has a sacculated expansion, the use of which is to pre- 

 vent the necessity of rapid respiration, thereby pro- 

 longing the animal's power of remaining under water. 

 The venous blood is thus retarded in its course back 

 to the lungs, until the animal rises for a fresh supply of 

 air. During the action of diving, the nostrils are closed 

 by a muscular sphincter. Under ordinary circum- 

 stances seals can remain submerged from fifteen to 

 twenty minutes; and it is stated that, during sleep, 

 they will remain in this condition for as much as an 

 hour, without coming to the surface to breathe. The 

 shining, glossy, adpressed hairs are protected from an 

 injurious action of the water, by an oily secretion which 

 exudes from the skin. Their margins are sinuous, but 

 the long, stout, horny whiskers are uniformly smooth. 

 Seals are for the most part marine, but a few of them 

 pass up the mouths of rivers to fresh-water streams, 

 and even lakes. While at rest, they are usually seen 

 reposing on the ledges of rocks, and basking in the 

 sun ; and on being alarmed, they suddenly plunge into 

 the water for security. These animals, as is well 

 known, subsist principally on various kinds of fish ; but 

 they will also devour crabs, molluscs, and other oceanic 

 products. Fossil remains of seals occur in the miocene 

 and pliocene deposits. 



THE COMMON SEAL (Phoca vitulimi} Plate 12, 

 fig. 40 is an inhabitant of the northern seas generally, 

 and was formerly very abundant all along the western 

 coasts of the British islands, as well as those of France ; 

 now, however, it is comparatively scarce, except on the 

 shores of Scotland, and its adjacent northern and 

 western isles. The body of the seal is between four 

 aud five feet long, having an ashy or yellowish-grey 

 ground colour, which is indistinctly spotted with light 

 brownish-black patches ; it exhibits a cylindro-conical 

 form, gradually diminishing in bulk from the region of 

 the chest towards the short broad muz/le in front, and 

 towards the rudimentary tail behind. The eyes are 

 rather large, and protected by a few stiff hairs, forming 

 small eyebrows; the ears being fully-developed, and 

 scarcely visible. One of the most interesting peculiari- 

 ties by which this species is distinguished, consists in 

 the oblique disposition of tho molar teeth, producing a 

 slight overlapping of the ends ; this remarkable charac- 

 ter having been first pointed out by Professor Nilsson. 

 The brain is largely developed a fact which in some 

 measure explains that high degree of intellectual 

 manifestation, which the seal is capable of displaying. 

 Though very timid in the wild state, and very difficult 

 to approach with a gun, it is, nevertheless, extremely 

 docile in a semi-domesticated condition. From the 



