206 RECORDS OF THE AUSTRALIAN MUSEUM. 



and regular costse, the points of intersection with the rugae showing 

 signs of small tubercles or nodes. 



Obs. — The previous occurrence of Plioladomya in our Continental 

 Secondary rocks depends on the identification by the late Mr. 

 Charles Moore ^^ of a European species (P. ovulum, Ag.), in the 

 Oolite of Western Australia, and a debatable form figured by Mr. 

 R. Etheridge^^ from the Cretaceous of Gordon Downs, Queensland, 

 without specific name. 



The present species is of a very peculiar type, what with its 

 transversely elongated outline, depressed beaks, straight cardinal 

 margin, and want of an anterior end. The absence of an anterior 

 end, strictly speaking, and the oblique antero-ventral outline are 

 features seen in such Pholadomyoi as P. Icevhiscula, Ag., P. decorata, 

 Ag., P. cancellata, Ag., and so on. Strange to say, although P. 

 terra-regince is undoubtedly from our Cretaceous beds, the outline 

 is far more like two Infra-Liassic species — P. lagenalis, Schafh , 

 and P. lariana, Stop.,"" than it is to the generality of Cretaceous 

 forms. In the two species figured by Stoppani, the anterior end 

 appears to be wanting, as in our fossil, but the valves are devoid 

 of costee. To some extent there is a likeness to P. rostrata, 

 Matheron, as figured by Zittel,'-^ from the Gosau series, and P. 

 depacta, Hamlin," from the Syrian Cretaceous, but in both instances 

 an anterior end, more or less, exists, and the entire surface is 

 costate. Dr. M. A. Blanckenhorn figures another Syrian species to 

 which P. terra-regincc is somewhat allied — P. pedernalis, Roemer,^" 

 in so far as the absence of an anterior end and the presence of 

 nodulated costae on the centre of the valves, but lacking the 

 longitudinal extension of the valves seen in our species. In form 

 and obliquity the British Lower Greensand species, P. martini, 

 Forbes,'^^ is allied, but again differs in the presence of an appreci- 

 able anterior end. 



The cardinal or dorsal aspect of our specimen is worn, but I 

 believe a circumscribed area of limited extent existed. 



The specimen was collected and presented by Mr. W. H. 

 Blomfield. 



The sketches are by Mr. C, Hedley. 



18 Moore— Quart. Journ. Geol. Soc, xxvi., 1870, pp. 231-232. 



19 HtheriAge— Ibid., xxviii., 1872, p. 347, pi. xxv., f. 6. 



20 Stoppani — Pal. Lombarde, 3e Sorie, p. 43, pi. iii., f. 1-3, and p. 44, pi. 

 iii.f. 4-7. 



21 Zittel — Bivalven Gosaugebilde Nordost. Alpen, 1864, 1 Theil, pi. ii., 

 i.2a-c. 



22 Hamlin— Mem. Mus. Comp. Zool. Harvard, x., 3, 1884, pi. vi., f. 6 a- & ; 

 Blanckenhorn — Beitriige zur Geol. Syriens : Entwickelung Kreid. Mit.-Nord- 

 Syrien, 1890, pi. v., f. 12 a -6. 



23 Blanckenhorn — Loc. cit., p. 94, pi. v., fig. 13. 



a4 E. Forbes-Quart. Journ. Geol Soc, i., 1845, p. 288, pi. ii., f. 3. 



