g 1 8 Nichtgehaltene Vorträge. 



is maintained here. In birds one would expect to see a variety 

 in the pelvie extremity, this is very pronounced, and has evident 

 regard to function. Birds are imilative, and so are susceptible of 

 evolution along that line. Beaks and toes are the chief avenues 

 for mechanical imitation. (The voice apparatus is only available 

 in some.) It is this change of shape in mechanical apparatus that 

 one places stress upon, the muscle foree „selects" the apparatus. 

 The muscles give points of purchase and rest, where skeletal ele- 

 ments may be deposited. A change in habit may lead to a change 

 in nutrition, which may be transferred to an adjacent more active 

 part. The numerous phalanges in the digits of whales have been 

 again and again commented upon, the additional phalanges are 

 formed in the prolonged flipper, and additional ray fingers are 

 produced along the outer margins of the flippers in Ichthyosaurs 

 (Several) and are not apparently of ancient date. There may be 

 many of these in the ancient sea lizards. Referred toby Williston 

 and Gilmore. Globiocephalus (in Cetacea) carries the palm with 

 12 — 14 phalanges in the 2nd finger, and 9 phalanges in the 3rd. 

 There are, however, more phalanges in 2nd and 3rd finger of 

 Cetacea than in the ist, 4th, or 5th, so it seems the lines of force 

 extend along these rays. 



There is a little difference to be seen between the metacarpals 

 of the 3rd and 4th fingers of Elephas. The latter is narrower at 

 the base. Primates have a primitive condition of manus and pes, 

 with some exceptions. The functions of the mouth as a pretensile 

 organ have been largely conveyed to the limbs of these animals. 

 The result is, as everyone knows, successful. The thumb is small 

 or somtimes absent. In Ateles a prehensile tail makes up, in part, 

 for the aborted thumb. Prehensile tails are, however, found in 

 other groups. The Lemurs are of interest because of their arboreal 

 habits. They are perfectly adapted for this form of life, and show 

 the fourth finger and fourth toe as longest of all. The first pha- 

 langes of the fourth are the longest in Galago and the Ruffed 

 lemur. The same holds for the second finger, the 3rd phalanges 

 of the fourth toe are longer than the 3rd phalanges of the other 

 toes. The increase in length of the fourth seems to produce auto- 

 matism in the entremitas which should be usefal at night. 









Gala 



g°- 









oes 



Metatarsal 



ist 



Phalanx 



2nd 



Phalanx 



3rd 



Phalanx 



1 



1.9 





1.9 





0.7 







2 



1.4 





1.3 





o,5 





0,65 



3 



1.6 





1-7 





0.9 





0.58 



4 



1.6 





1.85 





1.1 





0-5 



5 



r.6 





i-5 





0,7 





0.4 



