BY n. H. SCOTT 



1913. 



Tongue Bones— so called-— 



basihyal — a single 



bone. 



109 



)lid 



Tongue Bones — so called — 

 basihyal — in three pieces 

 — viz', 1 true basihyal, and 

 2 thyro-hyals — all distinct 

 moieties. 



A careful examination of these data ^Yill prove that the 

 epiphyses in the smaller toothed whales ankylose up accord- 

 inc to the same general rules as those that govern the growth 

 of land vertebrates generally, including man himself, i here- 

 fore a dolphin with its liumeral epiphyses closed, and only 

 tlie distal opiplivses of the radius and ulna open, is very 

 close to the standard of full growth. This conclusion is also 

 reached bv another method of computation, namely, by 

 tahino- the\actual lengths of the two dolphins under review, 

 a proceeding which yields a four-fifths growth for the imma- 

 ture creature. Eeverting now to the fossiUvha e :^In he 

 arm of this animal all the epiphyses, both proximal and dista , 

 are open, and therefore if it belongs to a genus m which 

 ankylosis takes place at maturity the animal may be tairly 

 assumed to be less than four-fifths fully grown and perhaps 

 only half grown. ,, . ^ -, , -, 



From mv personal knowledge of the smaller whales, added 

 to such comparative tests as are available to me, I should say 

 the animal at the time of its death did not exceed 12 ieet m 

 lencrth. If this is correct, we are dealing with an animal 

 whose length at maturity did not exceed thirty feet and was 

 possibly less. Just here it may be convenient to say that 

 one arm of a whale may show more epiphysial deve opment 

 than the other, so that if two workers were to study these 

 arms without knowing their histoiy, one might grant the 

 whale a slightly more advanced age than the other woulcl- 

 all of which, of course, suggests the need for great caution. 



The humerus of this fossil whale is devoid of its proximal 

 epiphysis, but in the dolphin family this does not add to the 

 total length since the head is at right angles to the shaft it 

 we assume that the same rule applies to the fossil, we get the 

 following comparative measurements of the arm bones ot 

 three animals : — 



Fossil Whale. 



Humerus (including distal 

 epiphysis) 



^ 125 mm. 

 Radius (distal epiphysis 

 missing— 10 mm. allowed) 

 = 100 mm. 

 Ulna > distal epiphysis muti- 

 lated— 10 mm. allowed) 

 =- 130 mm. 



Turuops (fully grown T 

 foot male). 



Humerus \^adult) 



95 ram. 



Radius ;adult) 

 Ulna (adult) 



= 110 mm. 



85 mm. 



D. Deiphi^ (fully grown 

 S feet 1 inch). 



HumemsTa^luIt) 



Radius (adult) 



70 mm. 



: 90 mm. 



Ulna (adult) 



= 80 mm. 



