186 RECORDS OP THE AUSTRALIAN MUSEUM. 



((. Nou-plicate, almost smooth casts, a condition seen in examples 

 from G-erringong Cliffs, as figured by Morris.*^ (PI. xxviii., 

 figs. 5 and 6). 



h. Latei^lly uni-plicate, similar to an illustration by de Koninck.^ 



e. Laterally bi-plicate, answering to the var. (hirwiiiii, mihi.^ 



d. Nuilteradiate laterally (PI. xxx., tig. 2). 



e. Transversely-oblong, similar to var. frdnxcerfa, mihi.^ 



I have catalogued these five varieties all as var. hranxto7ieiis!s, rather 

 than attempt to attach the existing varietal names of the mature-form, 

 the characters so running into one another at times that differentiation is 

 difficult. 



The surfaces of man}- of these casts show pittings and short groovings 

 without and around the muscular impressions ; they appear to be confined 

 to these areas and are probably connected with the ovarian sj'stems. 



Locs. — Farley Railway Cutting at Farley, and Brauxton, Hunter 

 River District. 



Hors. — Lower and Upper Marine Series respectively. 



III. — Ge7itix Mseonia, Dana, 1847.10 



(American Journ. Sci. (2), iv., 1847, p. 158). 



Mffionia morrisii, i^/k hoc. 



(Plate xxviii., figs. 7 and 8.) 



*Sp. Clnirx. — Shell (internal cast), short, gibbous, the valves strongly 

 arched diagonally ; anterior ends convex between the boldh' rounded 

 margins and the median, oblique, open cinctui-es, which stiongly insinuate 

 the ventral margins ; posterior ends comprising nearly two-thirds of each 

 valve, rising gradually to the coi^d-like, prominent, slightly sigmoidal 

 diagonal ridges ; posterior slopes large, slightly concave, and each median- 

 ally travei-sed by a subsidiary diagonal ridge following the outline of its 

 principal ; when viewed posteriorly, the united posterior slopes bounded 

 by the cord-like diagonal keels present a strongly cordiform outline ; 

 anterior muscular scai-s quite marginal, elongately tiiangular in a longitud- 

 inal dii-ection, and concentrically ridged ; posterior scars oval, rather retired 

 from the posterior margins. 



Ohs. — This remarkable shell was brought to my notice by Mr. W. S. 

 Dun ; it is form Harper's Hill, and is clearly of the type of Md'oiiia curintita, 

 Morris, but much shorter, and in compariscni with the latter far wider 

 across the united valves. The diagonal keels are very prominent and the 

 posterior slopes so far flattened, or slightly concave, that when viewed 



* Morris — Strzelecki's Phys. Descrip. N.S.Wales, etc., ISiS, pi. xvi., fig. 1. 

 ' de Koninck — Foss. Pal. Nouv. Galles dii Snd, pt. 2, 1876, pi. xii., fi^;. 1. 

 « Etherid<,'e— Geol. Pal. Q'land, etc., 1892, p. 2-l«. 

 " de Koninck — Loc. cil., pi. xii., fig. lb. 

 ••'As Myonia. 



