567 
tolerably deep from the dorsal to tbe ventral. There is no definite evidence of the 
valves gaping, although some appearance of this does exist at the posterior end of one 
specimen. It was evidently a very much couipressed species. An example collected 
by Prof. T. W. E. David measures one and a-half inches in length. 
Loc. Maryborough {The late R. Daintree ; T. W. R. David— C oVlu.. David, 
Sydney). 
Eamily — TllIGrONIDAS. 
Genus — TRIGONIA, Bruejuiere, 1789. 
(Encycl. Mtithod. i., PI. 14.) 
Teigonia has eta, Ether idge. 
Trioonia mtsuia, Etheridge, Quart. Journ. Geol. Soo., 1873, xxviii., p. 339, t. 19, f. 2, 2a. 
Sp. Char. Shell triangular or deltoid, much produced or elongated at the 
posterior end ; anterior side truncated ; umboiies promineut and thick ; hinge area and 
teeth not preserved, save a few on the posterior area. {Etheridge?) 
Obs. We possess only the cast of this shell, and had it been found in the 
Cretaceo.us rocks of Britain we should have allied it to Trigonia alceformis, Park., or 
T. caudata, Ag., but from the umbo to the ventral margin it is much higher or deeper 
than either of the two forms referred to. I am inclined to believe that the concentric 
folds or ribs supported tubercles upon them, as in Trigonia scabra and T. caudata. 
I unhesitatingly refer it to the Cretaceous deposits, and it belongs to a type not known 
in the Jurassic rocks. T. sanotw-crucis, Pictet and Camp., much resembles this shell ; and 
again, Mr. C. L. Griesbach describes a Trigonia, from the Umtafuna Eiver, Natal, 
which has an elongated posterior end, and, in general shape and deltoid form, is much 
like our shell. {Etheridge.') 
The folds distributed over the umbonal region in Mr. Etheridge’s figure are shown, 
on the internal cast of a left valve obtained by Prof. T. W. E. David, to occur generally 
over the whole valve, except on the posterior slope. They are wide and flat. 
Loc. Maryborough {The late R. Daintree; T. W. E. David Colin. David, 
Sydney). 
Teigokia, sp. ind. {a.), PI. 26, fig. 5. 
Sp. Char. Cast subovately elongate, subconvex, but not inflated ; anterior side 
rounded from the umbones downwards, and but little produced; posterior side pro- 
duced into an obtuse, somewhat flattened, nasiform extension, with a straight oblique 
margin ; ventral margin rounded, extended, without apparent undulation or excavation 
posteriorly ; hinge-line concave, sloping towards the posterior end; umbones acute, little 
incurved, nearly vertical to the longer axis of the shell ; area narrow and elongate, 
bounded by a sub-acute ridge from the umbones, which gradually dies out ; escutcheon 
not preserved; dental sockets oblique, divergent, the anterior tear-slinped and long, the 
posterior thin ; flanks of the cast but little convex, whilst the posterior end immediately 
below the bounding earina of the area bears a depression or groove. 
Ohs. An exceedingly well-preserved cast, which appears to differ from any of 
the hitherto described Australian Trigonias, but is probably nearest to T. mesembria. 
Woods It differs entirely in shape from T. lineata, Moore, and is not sufficiently 
pointed at the posterior end for T. nasuta, Etheridge. In many points this cast agrees 
with Trigonia conocar diiformis, Krauss,* from the Cretaceous rocks of South Africa, but is 
* Nova Acta Acad. Cses. Leoii.— Carol. Nat. Curio., IS.'iO, xxii., Tars. 2., p. 454., t. 49, f. 1. 
