174 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. 



with double cross-ridged molars, similar in number to those in Di- 

 jprotodon, and presenting the same inferiority of size as the upper 

 molars of the present fossil from Darliag Downs show. lir. George 

 Bennett has inscribed the name " Zygomaturus" beneath the sketches 

 he has transmitted, and informs me by letter, that such is the name 

 which Mr. Macleay has provisionally given to the fossil in the 

 Catalogue of the Sydney Museum. 



The bony palate appears to have been entire, or without any un- 

 usually large palatal vacuity, in this respect resembling the same 

 part in Macropus major and Diprotodon. 



Whether this fossil prove to be a second species of Diprotodon, or 

 a distinct genus ; and in the latter case, whether distinct from No- 

 toiherium, or identical with it, — it forms the most extraordinary 

 addition to the evidences of those extinct phytophagous quadrupeds 

 of Australia which exhibited the marsupial type on a scale rivalling 

 the Hhinoceroses and large BuiFalos of the warmer parts of the 

 Asiatic and African contiaents. Let us hope that good plaster casts 

 of the unique specimen may be made and transmitted to Europe, to 

 enable a further insight into its nature and affinities. 



Notes on the Photographs. — Since the foregoing notes were penned 

 I have had the opportunity, through the kindness of Sir R. I. 

 Murchison, to inspect the photographs and photographic stereoscopes 

 of the skull to which the name Zygomaturus trilobus has been given 

 by Mr. Macleay. 



The photograph, No. 4, shows most satisfactorily the close simi- 

 larity of the two-ridged crowns of the upper teeth to those of the 

 Biprotodon australis, figured in pi. 2 of my '* Report on the 

 Extinct Mammals of Australia"*, and removes whatever doubt 

 might have been left after inspecting the pen-and-ink sketches by 

 Mr. Geo. Bennett, as to the order of succession of the last four 

 grinders, as indicated by the degrees of attrition of their crowns. 



The same important evidence of the marsupiality of the species is 

 yielded by the teeth in the two portions of upper jaw figured in the 

 stereoscopic views beneath the principal fossils. There is a low 

 transverse basal ridge before and behind the two chief ridges ; these 

 are slightly bent, with the concavity looking backwards : they have 

 not the connecting processes extending from the fore part, as in 

 Macropus, and herein lies the generic distinction from the Kangaroos ; 

 but the close conformity between Macropodidce, Zygomaturus, and 

 Biprotodon in all the minor modifications of the crowns of the 

 grinding teeth, as well as in their number, relative size, and order 

 of succession, bespeaks in an equal degree their family relationship. 



The extent of each molar series in Zygomaturus is about 7 

 inches ; in Biprotodon it exceeds 8 inches : the attachment of the 

 front pier of the zygomatic arch in Zygomaturus is opposite to and 

 almost coextensive with the three middle grinders (Plate IX.f 



* ' Report of the British Association,' 1844. 

 t See the next Memoir. 



