38 E. BEOWN ON THE SEALS OF GEEENLAND. 



After a very careful examination, Dr. Wallace informs me that 

 he could not find them in all the Seals which he examined. 

 He certainly remarked the dilated condition of the veins, but 

 referred this to a physiological cause, viz., the pressure of the 

 superincumbent column of blood. He believes that their power 

 of remaining so long below the surface of the water is to be 

 referred to a cause physiological, and not structural. Their 

 expertness in swimming is not possessed from birth, but only 

 developed from an innate instinct. We have often watched young 

 Seals taking the water at first in smooth pools among the ice, 

 and then swimming slowly and quietly about in^the still floe-water, 

 — then gradually taking the water, staying below the water at 

 first but a short time, gradually lengthening their stay until they 

 had acquired the faculty of remaining the usual time beneath 

 the surface. Dr. Wallace, then, thinks that this faculty is 

 owing to a cause more physiological than anatomical, and that 

 the explanation he has given, coupled with the enormous quantity 

 of blood which the Seal contains, will account for their power of 

 remaining beneath the water. As I have not examined the 

 anatomy of the Pinniped ia with this object in view, I cannot 

 presume to give an opinion on the matter ; in the Narwhal and 

 other Cetacea which I examined, the extensive venous plexus 

 about the vertebral column seemed to explain the possession of 

 this power of temporary subaquatic existence. The flesh of the 

 Seal is quite black, from the enormous quantity of venous blood 

 it is impregnated with ; but if exposed to the air or steeped in 

 water, it acquires the usual arterial rosy hue. The flesh of young 

 Seals which have not yet taken the water is, on the contrary, 

 quite red. 



3. Hahits and Instincts of Seals in general. 



They spend a considerable part of their time in feeding, but they 

 pass by far the greater part in basking in the sunshine and sleep- 

 ing on the ice.* It has been remarked that the Seal sleeps and 

 wakes alternately about every 180 seconds. Seals are, however, 

 often killed in considerable numbers when asleep on the ice ; and 

 this happens most commonly on a day of warm sunshine. We 

 had a Seal on board about a month old, which I watched atten- 

 tively for some time, and it certainly seemed to wake and sleep 

 alternately, with the interval mentioned ( Wallace) : when dis- 

 turbed it made attempts to defend itself; and if left alone for a 

 few seconds, it drew its flippers close to its sides, and gradually 

 it began to look drowsy, then closed its eyes, and, from the 

 long deep breathing, it was evidently asleep for a minute or two 

 (the time varied) ; and then, without being disturbed in any 

 way, it would suddenly open its large black glassy eyes, stretch 

 out its head, and look about, and, as if satisfied that all was right, 

 would again relapse to sleep, and so on. When aslieep they 

 always leave several sentinels on the watch, which, strange to 



* " Stemunt se somno diversae in littore Phocse " (Virgil, GeorgicS; lib. 4). 



