1910.] AXD BIOLOCJV OF THE LARGER CETACRA. 791 



the ol)je(!tion will l)e raised that if stones are found on the under 

 surface, how is one to make sure how long they have been tliere ? 

 On this point I was assured by my informant that the stones ai'e 

 generally so lightly attached that they soon fall oti", and a whale 

 could not travel far with them. If we may assume tliat this is 

 correct, when a whale is captured with stones on the ventral 

 surface it is only necessary to ascertain the depth of the sea at 

 the locality of capture, by referring to the chart, to ascertain the 

 depth to which the creature has dived on being harpooned. It is 

 sa.L<l by the whalers that when a hai'pooned whnle, after breaking 

 the harpoon-i-ope, dives to a depth of 60 fathoms and dies, it comes 

 to the surface at the end of three days ; whei-eas if it goes below 

 this depth and dies it never reappears. There seemed to be 

 luianimous agi'eement among the whalei'S upon this point. 



3. Copulation, Period of Gestation and Hate of Breeding. 



The Balcenoptera are said by whalers to copulate at the sni-faee 

 of the sea. The pair swim towards encli other and tui-n slightly 

 on their sides so that their ventral surfaces face one another. The 

 male makes several dashes at the female to insert the penis. 

 When the pair first rush together the long axes of their bodies 

 are parallel with the surface of the sea ; but they curve up 

 vertically at the end of the act. After copulation the male is said 

 to be exhausted and easily caught. 



As regards the period of gestation and the rate of breeding 

 among Cetaceans, it is difficult to see how any deiinite information 

 can be obtained on these and similar sulijects, which are of 

 interest to the cetologist and of consideraljle importance com- 

 mei-cially, unless individuals are kept in a confined place for 

 purposes of observation. This would perhaps not be such an im- 

 possible undertaking as it would at first appear-. Of the many 

 deep sounds or straits, through which the tides pass, on the 

 western coasts of Ireland and Scotland, one could doubtless be 

 found which could be converted into an aquarium for whales. To 

 do this it would only be necessaiy to place barriers at the mouths 

 of the strait in order to imprison the animal and yet allow of the 

 ingress and egress of the tide and food-supply. The animals 

 would have to be caught by the Japanese method of capturing 

 whales, which consists of throwing a large rope-net over the iinimnl 

 and towing it to the shore alive. Balcena hiscayensis Gray, has 

 been taken hj this method and possibly other species also *. 



A Whalebone Whale imprisoned in a strait coidd probal)ly be 

 kept alive on the organisms swept in by each tide. 



Until some such scheme as this is brought to pass we must 

 continue to remain in ignoiance, or be content with vague 

 speculations, concerning many points in the biology of the lai-ger 

 Cetacea. 



* K. Mobius, Sitzuiigsbi'iielite iliT Akadeinie iler Wissensoliafteii /u Hi'vliii. lii. 

 1893. 



