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355 



were accompanied by an escape of air bubbles from the blowhole. While 

 some animals were seen to copulate only once and then to go their separate 

 ways, others repeated the act a number of times in the space of half an 

 hour. In the Californian aquarium, Brown and Norris observed that 

 Bottlenose bulls made sexual advances not only to cows of their own species 

 but also to Lagenorhynchus obliquidens, a N. Pacific White-beaked Dolphin, 

 which they approached fifty times within thirty minutes, though only a 

 few of these approaches resulted in copulation. Apparently the White- 

 beaked cows were in season while the Bottlenose cows in the tank were 

 not. Nothing is known about any offspring of such mixed unions (if, 

 indeed, they are ever born), except that Fraser (1940) described three 

 skeletons discovered in Ireland which looked very much like crosses 

 between Bottlenose and Risso's Dolphins. 



There are few other descriptions of the mating of dolphins. Hamilton 

 (1945), Nishiwaki (1958) and Caldwell (1955) have reported fairly quick 

 acts of copulation in a lateral surface position on the part of Rough- 

 toothed Dolphins (Steno rostratus). Killer Whales, and Spotted Dolphins 

 {Stenella plagiodon) , and Wilcke and his colleagues (1953) believe that they 

 have observed the mating of Lagenorhynchus obliquidens off the coast of 

 Japan, but have given no details. A Dutch fisherman reported that he saw 

 two porpoises copulating in the vertical position off Texel (January 1958), 

 and Spencer described the same behaviour in two Belugas (Hudson Bay) 

 as early as 1889. According to Vladykov, four Belugas often pursue one 

 and the same cow. 



One of the best descriptions we have comes from Th. Carels, first mate 



Figure ig6. 

 Pilot Whale sur- 

 facing after 

 vertical copulation 

 {Photograph : 

 Th. Carels.) 



