94 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



a beautiful case of the phenomenon of convergence. A third 

 method which has been adopted for giving an increased surface 

 to the nipper is well shown in the Ichthyosauria. This consists 

 in the splitting of the fifth digit into two. 



With regard to the observed number of digits there is a 

 difference in the two large groups of whales — toothed whales 

 and whalebone whales. The toothed whales have five digits. 

 The whalebone whales are generally said to have four digits, 

 except Balaena, the Right Whale, which has five. The matter 

 does not seem quite as simple as this, however. In the Rorquals 

 (Balaenopteridae) there is often present a small element which 

 has been considered to be a vestigial thumb (digit No. 1). 

 This is followed by four well-marked digits, each exhibiting 

 hyperphalangy, digits No. 3 and 4 in this series having six, 

 seven, or even eight phalanges each. 



Kiikenthal* made a detailed study of the flipper skeleton 

 in a number of foetuses both of toothed and whalebone whales, 

 and discovered some new facts which are of considerable 

 importance in the interpretation of the hand skeleton of these 

 forms. Since this paper the only author who has published 

 a paper of any great importance on the subject is Kunzef, 

 though various authors have quoted Kiikenthal with more or 

 less approval. J 



Some flippers from small whale foetuses have come into 

 my possession, and on examination they show very clearly an 

 interesting condition found by Kiikenthal. Since small whale 

 foetuses are not easily obtained, I have considered the specimens 

 of sufficient interest to warrant their exhibition to the Society, 

 accompanied by a short note on the general phenomena shown 

 by them. 



* Kiikenthal, W. " Walthiere " in Denkschr. Med. Nat. Gesells. 

 Jena, 1889-93. 



t Kunze, A. Zool. Jahrb. Anat. Vol. 32, p. 577. 



± e.g., Allen, G. M. Mem. Boston Soc. Nat. Hist. Vol. 8, No. 2, 1916. 

 p. 191. 



