8 



STUDIES OF TASMANIAN CETACEA, 



The Skeleton. 

 The axis and atlas vertebrae are always ankylosed in 

 these whales, the rest of the cervicals being quite free. 

 The vertebral formula is fairly constant, and may be 

 given as follows : — 



Cervicals — 7. 



Dorsals = 14 (some cetologists say 15). 



Lumbar s = 22. 



Caudals = 32 = 75 — with a maximum of 76. 

 Accidental mutilations of the vertebrae are common, even 

 among young animals, owing to the custom of diving 

 under ships in rapid motion. Such effects usually mani- 

 fest themselves in the shape of exostosis, which may cither 

 simply cover«the elements involved, or by partial absorp- 

 tion and subsequent accretion, materially alter the contour 

 of the bones. We hold various instances, in our respective 

 collections, of these naturally healed wounds. The true 

 lumbar vertebrae are devoid of zygapophyses, but they 

 appear in a functionally reduced state on the chevron- 

 bearing portion of the caudal series;, having doubtless 

 reference to muscular attachment areas rather than any- 

 thing else. The neural spines slope gradually backwards 

 through half of the dorsal series, assume a recovery in the 

 second half, and become vertical in the middle of the lumbar 

 series — approximately the twenty-eighth vertebra from 

 the skull. The chevron-bearing series (or as we might 

 call them sacro-lumbars, although usually simply included 

 in the caudal series) begin by being approximately verti- 

 cal, as regards their neural spines, and end by having 

 them pitched at a slope that closely simulates that which 

 obtains in the middle dorsals. In the two animals dis- 

 sected by me, the following express the sizes of the neu- 

 ral spines, and neurapophyses of the last dorsal that 

 reaches the sternum, and the largest lumbar of the series ; 

 in other words — the twelfth and twenty-eighth vertebrae, 

 from the skull. 



