356 PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



at the base, less so, however, than in Protkylacyitus. Regarding the hind 

 limb, two alternatives are possible. Either the tibia was short and the 

 back sloped downward from the shoulders, or the hip and shoulder were 

 equally elevated. The latter assumption seems preferable and an elon- 

 gated tibia and fibula have been supplied, as in Thylacynus. An ossified 

 patella has been introduced from analogy with Prothylacymts. The planti- 

 grade pose is largely conjectural, as there is no certain means by which 

 the gait of an animal may be determined from the skeleton of the fore 

 foot alone. It is probable that Frothy lacy ttus, Cladosictis and Amphi- 

 proviverra were plantigrade, and, in the absence of evidence to the con- 

 trary, the same may be assumed tentatively for Borhyana. No trace of a 

 clavicle is preserved, but one has been inserted from analogy with exist- 

 ing carnivorous marsupials. 



Habits. Some inference regarding the pugnacity of these animals may 

 be drawn from the large cicatrice in the mandible of B. tuberata repre- 

 sented in fig. 3, PI. XLV. Ability to trail by scent like the Tasmanian 

 thylacyne may, perhaps, be inferred from the large olfactory sinuses. The 

 blunt claws indicate adaptation to terrestrial progression. The animal 

 undoubtedly preyed on the larger placental mammalia. 



BORHY/ENA TUBERATA AmeghinO. 



(Plates XL-XLII ; XLV, Figs. 2-6 ; XLVI, Figs. 1-3* ; LII, Fig. I ; LIII, Figs. 2, 20, 9, ga ; 

 LIV, Figs. 7, 13; LXI.Fig. 3.) 



Borhycena tuberata Amegh.; Enum. Sist. Especies Mamif. F6s. Patagonia 



Austral, p. 8, Dec., 1887. 

 Borliyccna zitteli Amegh.; Enum. Syn. des Especes de Mam. Fos. des 



Formations Eocene de Patagonie, pp. 119-120, 1894; Bol. Acad. 



Cordoba, p. 375, 1894. 



A nearly complete skull and mandible (No. 15,701) associated with a 

 considerable portion of the skeleton, secured by Mr. Peterson eight miles 

 south of Coy River, has been identified with this species, which is one of 

 the largest of the Santa Cruz thylacynes. 



Apart from characteristic measurements, B. tuberata may be recognized 

 by the broad depressed skull, perfectly flat between the orbits, with robust, 

 gradually expanding arches. The face is without antorbital constriction. 

 The postzygomatic portion of the brain case is considerably elongated and 



