“TERRA NOVA” EXPEDITION. 
42 
Recently some American writers * claim to have proved the relationship of the 
Sparassodonts of Ameghino, Borhyaena, Prothylacinus, ete., of the Miocene of 
I to} ? > e b > 
Patagonia to the Tasmanian 7’hylacinus, and even unite them in a family Thylacinidae, 
distinct from the Dasyuridae ; for this there seems to be but little justification. 
Fie. 7.—Skulls of A, Borhyaena tuberata (after Sinclair) ; B, Phascologale dorsalis (after Thomas), and C, 
Thylacinus cynocephalus ; seen from above. Phascologale has been selected for comparison as a small 
insectivorous type, differing from the large carnivorous Thylacinus in the form of the cranium and 
zygomatic arch, but resembling it in many important structural characters. 
Tomes} has shown that in Borhyaena the enamel of the teeth resembles in 
structure that of Creodonts and Carnivores, lacking tubules, and with the groups of 
* Sinclair, Rep. Princeton Exped. Patagonia, 1v, 1901, p. 333; Gregory, Bull. Amer. Mus. xxvm, 
1910, p. 207. 
tT Proc. Zool. Soc. 1906, 1, p. 45. 
