NO. 8 INTERRELATIONSHIPS OF THE CETACEA WINGE 49 



^ (P. 4.) Much information about the structure of the hand in 

 the Cetacea has been collected by Kiikenthal (Die Hand der Cetaceen ; 

 Denkschr. d. med. naturw. Ges. zu Jena, vol. 3, pt. i, 1889, pp. 23-69, 

 pi. 3, and the section " Die Brustfiosse," in Vergl, -anat. u. entwicke- 

 lungsgesch. Unters. an Walthieren, ibid., pt. 2, 1893, pp. 267-312, 

 with illustrations) and Kunze (Ueber die Brustflosse der Wale; 

 Zoologische JahrbiJcher, Abt. fiir Anatomic, etc., vol. 32, pt. 4, 1912, 

 pp. 577-651, pis. 33-35), both of whom give references to earlier 

 works. 



Kiikenthal regards it as most probable that the large number of 

 phalanges in the Cetacea has originated as follows : That the diaphy- 

 ses and epiphyses in an ordinary hand whose fingers had mostly three 

 phalanges have loosened themselves from each other, and have be- 

 come independent and uniform, all of them ossified. This explana- 

 tion cannot possibly be right. It is immediately contradicted by the 

 fact that in cetacean hands with many- jointed fingers there can be 

 found both diaphyses and epiphyses, ossified, in the larger of the 

 phalanges that are present, as Kiikenthal himself has observed. If 

 one examines series of adult cetaceans' hands or of embryo hands, it 

 is quite impossible to detect anything that could point in this direction. 

 It certainly should be possible to find, somewhere or other, transition 

 forms which would show indication that the phalanges were of unlike 

 origin, some of them diaphyses, others epiphyses ; but of this there is 

 not the slightest evidence. Neither is it probable that the forerunners 

 of the whales among terrestrial animals, had, even when young, 

 epiphyses at both ends of all the phalanges, as would be needed in 

 order to explain even tolerably the large number of joints in the 

 Cetacea. It is true that in the Cetacea there have arisen super- 

 numerary ossified epiphyses, more epiphyses than in their ancestors. 

 But let it be noted that this has only happened in those Cetacea that 

 already had acquired many-jointed fingers. (The objection to the 

 " epiphysis-hypothesis " that it could at most explain the presence of 

 only 12 joints in the fingers, including the metacarpal, and that it 

 therefore cannot hold good where the number of joints is more than 

 12, is met by Kukenthal with the admission that in such instances the 

 number of joints is actually increased out beyond the finger tips. 

 /. c, 1893, p. 3II-) 



Another explanation which is more probable Kukenthal himself 

 sets forth but regards as less happy : " Wiirde man die Entwicke- 

 lungsgeschichte allein zur Losung der Frage heranziehen, so wiirde 

 sich der Schluss ergeben, dass ausser den vier typischen Finger- 



