AND OTHER SPECIES OF CEPHALORHYNCHUS. 629 



Liouville (1913, p. 165), in a discussion, under the heading of 

 Lagenorhynchus fitzroyi, of certain Dolphins which have been 

 recorded as L. cruciger or by other names, comes to the conclusion 

 that a number of conspicuously marked Southern Dolphins, 

 recorded under various specific names, are colour-varieties of a 

 single species. Whether this view be correct or not, the con- 

 cordant evidence derived from several distinct sources, with 

 regard to Commerson's Dolphin, shows that this species at least 

 is remarkably constant in the position of its areas of black and 

 white. It may be suggested that these striking markings have 

 the protective value which has been ascribed to the " disruptive" 

 type of coloration in animals. As seen in the water, the white 

 area probably divides the body into two parts which seem to 

 have little, if any, connection with one another. The Dolphin is, 

 in fact, effectively camouflaged, and perhaps the protection is 

 specially successful in water liable to contain floating ice. The 

 principal enemy of Commerson's Dolphin is probably Orcinics, 

 the Killer Whale. 



The British Museum has recently received the following- 

 material, referable to the genus Cephalorhynchus, in which I 

 place Delphinus commersonii J^SiceT^. {=: Lagenorhynchus JJoioeri 

 Moreno and L. cruciger Bruce, nee auctt.) : — • 



A. An eviscerated male specimen (in salt), 4 feet 6 inches long, 

 captvired in Stanley Harbour, Falkland Islands ; presented by 

 Mr. J. E, Hamilton, Magistrate of West Falkland, Avho stated 

 that the stomach contained "krill" (the Norwegian whalers' 

 name for the small Crustacea which form the food of Whalebone 

 Whales) and the pens of cuttlefish. The vertebral epiphyses are 

 quite free, and the animal was accordingly immature. 



B. A skull, with lower jaw, picked up on the shore of Byron 

 Sound, West Falkland ; presented by Mr. Rupert Yallentin. 



0. Two photographs of a specimen stranded in the Falkland 

 Islands on another occasion ; presented by Mr. Rupert "Vallentin, 

 who stated that these Porpoises are fond of basking in the beds 

 of Macrocystis when the sun is shining, and that he knew of no 

 other species in that locality. 



D. A note-book, lent by Mr. Lionel E. Adams, containing 

 observa,tions on Dolphins observed by him from a ship in the 

 Straits of Magellan, together with a small photograph showing 

 two of them in the air during a jump out of the water. The 

 note-book included an excellent sketch, completely agreeing with 

 A and C, and the passage "Jet black and pure white (no 

 '•' shades). I did not see any vai^iation in the markings of one of 

 "the hundreds that played about the ship." 



The following notes were made on Mr. Hamilton's specimen 

 (PI. I. figs. 1 & 2) before its skeleton was prepared. The skin, 

 although somewhat abraded, showed the external coloi-ation 

 perfectly distinctly. 



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