314 Mr. R. Etheiidge, Jnr., on 



Mylodon? australis, Krefft, N. S. Wales Votes & Pro- 

 ceedings, V. 1882, p, 558, 14tl) numbered pi., 

 figs. 7-y. 



II. The Ungual Phalanx Provisionally Catalogued 



AS TSTLACOLEO BY LyDEKKER. 



Mauy years ago a plaster replica of another of Krcfft's 

 specimens *, described iu MS. as the " nail-bone of the hind 

 foot of a gigantic Phalanger, probably a small Zygoinatarus, 

 Nototherium, or Diprotodon " was forwarded to the Geologi- 

 cal Department of the British Museum (Natural History). 

 I surmised this might be No. M. 1523 f of the ' British 

 Museum Catalogue of Fossil Mammals,^ part v. (p. 195) 

 catalogued by Lydekker as " cast of an ungual plialangeal " 

 provisionally of Tht/lacoleo ; by correspi^ndence Dr. A. S. 

 U'oodward confirmed this. The original bone is preserved 

 here and is slightly imperfect ; it is from the Wellington 

 Craves, and bears the number A. 13'320 (PL XVIII. fig. 2). 

 It is manifest, if the sheathed nail-bones {'^ Mylodun") are 

 referable to Thylacoleo, following Orten, such an arched, 

 laterally compressed and naked bone, one of those spoken 

 of by KrefFt as " large nail-l)ones . . . evidently those of a 

 Phalanger *' ;}:, cannot. One of these § is probably the 

 original of both Owen's illustrations of his non-sheathed 

 Thylacoleo ungual phalangeal. Our collection contains five 

 of these bones^ four from the Wellington Cave-; ossiferous 

 breccia (Pis. XVIII.-XIX. figs. 2-9), the fifth from Cope's 

 Cz'cek, probably from a thermal mud-spring deposit (PI. XX. 

 figs. 10-12). These vary much in size and degree of dorsal 

 curvature, and for the convenience of description may be 

 taken separatelv. 



Type 1.— The phalanx in question || (PI. XIX. figs. 8 & 9) 

 is highly arched, compressed laterally, the dorsal edge thin, 

 shaip (trenchant), the degree of curvature almost equal to 

 the quadrant of a circle, the general appearance of the bone 

 being decidedly h'>ok-like. The proximal end is imperfect, 

 the articular surface and the plantar tuberosity gone; it is 

 '6b mm. wide, and in thickness 8 mm. 



The second example never seen by KrefFt or Owen 

 (PI. XX. figs. 10-12) is a more perfect specimen, one in 



* Kreflft, ' Caves and Rivers Report,' jtl. 14 (numbered), fig. 12. 

 t Dr. A. S. Woodward informs mn this should read 1536, 

 t Krefft, loc. cit. pi. 14. (numbered), (igs. 11 and 12. 

 § Krefft, loc. cit. MS. df-scription of pi. 14. fig. 11. 

 II Krefft, loc. cit. pi, 14. (numbered), fig. 2. 



