LOWER CRPrrACKOUS FOSSILS — KTIIERIDGE. 319 



possesses a less number of whorls and a more telescopic concave 

 aspect. 



PELECYPODA. 



Genus PsEUDAVicuLA, Efh. JiL, 1892. 



(Geol. Pal. Q'land, &c., 1892, p. 449). 



Obs. — In my original description, lacking evidence to the con- 

 trary, I accepted Moore's statement" that the type species 

 (Lncina aytomala, Moore) was equivalve. I have now material 

 to show that the shell, I have for years rightly or wrongly named 

 Fseudavicnla aihomala, Moore, sp., is decidedly inequi valve. The left 

 valve is the more convex, the umbo higher than in the right, and 

 slightly overhanging the cardinal margin, the umbo of the right 

 valve is depressed and does not project above the cardinal margin. 

 Later acquired specimens of P. australis, Moore, sp., lead to the 

 belief that such is also the ca.se in that species, as it certainly is 

 in the one to follow. 



PSEUDAVICULA PAPYRACEA, sp. 110V. 



Undetermmed Bivalve, Eth. fil., Geol. Pal. Q'land, ivc, 1892, 

 p. 482, pi. xxi., f. 14. 



Sp. Char. — Shell suborbicular, delicate and fragile, compi-essed, 

 posteriorly alate, test very thin, papyraceous. Left valve convex 

 in the umbonal region, with a sharply-pointed rather elevated 

 umbo. Right valve more depi-essed than the left and the umbo 

 inconspicious. Dorsal margins on both sides straight, those 

 anterior to the umbo obliquely inclined, those on the posterior 

 straight ; anterior ends small, the margins rounded ; posterior 

 alations small, tiat, the margins rectangular. Sculpture of micro- 

 scopic concentric lines. 



Ohs. — This very delicate shell, or fragments of it, occurs through- 

 out the Pachydomella calcareous mudstone, of which so much of the 

 collection is made up, in lai'ge numbers in association with the 

 still more common PachydomeJla chat us. In not a single instance 

 have I seen the test complete in any one specimen, the usual con- 

 ditions being that of internal casts, or the latter with fragments 

 of test adhering, which must have been very thin and fragile. 



' Moore— Quart. Journ. Geol. Soc., xxvi., 1870, p, 251. 



