346 



PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



and both manus and pes are pentadactyl in Amphiprovi'verra and Clado- 

 sictis. 



7. The trochlear surface of the astragalus in the Santa Cruz forms is 

 short and flat with feebly differentiated facets for the tibia and fibula. 

 This has been interpreted as indicating a plantigrade gait. In the digiti- 

 grade Thylacynus the astragalar trochlea is both longer antero-posteriorly 

 and more deeply grooved. 



8. There is no trace of syndactyly in either the living Tasmanian or 

 extinct Patagonian thylacynes. 



9. The pubes do not appear to have supported epipubic ossifications in 

 Cladosictis. In the only specimen of Prothylacynus in the Princeton col- 



FIG. 5. 



Thylacynus cynocephalus. a, fifth and sixth lumbar vertebrae from the right side ; b, atlas from 

 above ; c, atlas from below ; d, cervical series from the left side. All figures x \. 



lection the pubes are not preserved and the entire pelvis of Borhycena 

 and Amphiproviverra is unknown. In Thylacymis the epipubic elements 

 are mere vestigial cartilages (text fig. 3). 



