314: Mr. R. Etheridge, Jut., on 



Mylodunt australis, KrefFt, N. S. Wales Votes & Pro- 

 ceedings, v. 1882, p. 558, 14th numbered pi., 

 figs. 7-9. 



II. The Ungual Phalanx Provisionally Catalogued 

 as Tkylacoleo by Lydekker. 



Many years ago a plaster replica of another of Krefft's 

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

 foot of a gigantic Phalanger, probably a small Zygomaturus, 

 Nototherium, or Diprotodon" was forwarded to the Geologi- 

 cal Department of the British Museum (Natural History). 

 I surmised this might be No. M. 152b' f of the ' British 

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

 catalogued by Lydekker as (t cast of an ungual phalangeal " 

 provisionally of Thylacoleo ; by correspondence Dr. A. S. 

 Woodward confirmed this. The original bone is preserved 

 here and is slightly imperfect ; it is from the Wellington 

 Caves, and bears the number A. 13320 (PI. XVIII. fig. 2). 

 It is manifest, if the sheathed nail-bones ( tl Mylodon") are 

 referable to Thylacoleo, following Owen, such an arched, 

 laterally compressed and naked bone, one of those spoken 

 of by Krefft as " large nail-bones . . . evidently those of a 

 Phalanger " J, 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 

 Creek, 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 separately. 



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

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

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

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

 being decidedly hook-like. The proximal end is imperfect, 

 the articular surface and the plantar tuberosity gone ; it is 

 35 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 



* Krefft, ' Caves and Rivera Report,' pi. 14 (numbered), fig. 12. 

 t Dr. A. S. Woodward informs me this should read looo. 

 X Krefft, loo. cit. pi. 14. (numbered), tigs. 11 and 12. 

 § Krefft, luc. cit. MS. description of pi. 14. fig. 11. 

 || Krefft, luc. cit. pi, 14. (numbered), fig. 2. 



