On the elephant seal (Macrorhinus leoninus, Linn.) / by William H. Flower.

  • William Henry Flower
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: On the elephant seal (Macrorhinus leoninus, Linn.) / by William H. Flower. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    offset of the northern, because the only other known species of the CystophorincB is also northern.” Now it seems to me that if we are to accept the presumption that they are distinct upon geographical grounds alone, we must bid adieu to what little still remains to us, after the revolution of the last twenty years, of our conception and definition of a species. For how long in time and how far in space must two branches of one stock of animals be separated in order to constitute a claim to specific distinction 1 I should answer this question by saying, only either when they have become so far physiologically differentiated as no longer to interbreed (a point on which it is, of course, ex- tremely difficult to get evidence), or when permanent recognizable differential structural characters have been established. Until we are sure that they are either physiologically or morphologically distinct we have no grounds for separating them. In fact, by doing so, we are concealing or ignoring a most important zoological fact, viz. that under certain circumstances members of a group may become and remain for a long period of time isolated from the parent stock without appreciable variation from the original type taking place. Show any character in which the one has departed from the other, however small, so that it be constant and universal, then the case is altered, and it becomes a subject for consideration whether the amount of variation is sufficiently great to be consistently admitted as specific. But even this stage does not appear to be yet reached in the case of the northern and southern Elephant Seals. The evidence upon which Dr. Peters has based the four supposed species of southern Elephant Seal, viz. leonina, falklandica, probo- scidea, and Jceryuelensis, is still more shadowy; but these were only put forth by him as suggestions of possibilities, not as ascertained facts. P.S. Since the greater part of the above was written, I have heard from my friend Prof. Turner of Edinburgh that he has in his hands for description the skeletons of a male and of a female Elephant Seal from Kerguelen, and a skull of a large male from Heard Island, brought home by the * Challenger ’ Expedition. The latter, Mr. Moseley informs me, he selected as one of the largest out of hundreds which lay on the beach at the time of the ‘Challenger’s’ visit, Feb. 6, 1874 ; it is, however, considerably smaller than the specimen described above, having a condylo-premaxillary length of 20 inches (483 millims.) and an extreme length of 19 inches (508 millims.). It is to be hoped that this large additional material will soon be made available for reference. A good figure of the skull of an adult female is at present an especial desideratum. [18]
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