460 
incurved ; anterior and ventral margins rounded ; surface bearing radiating costae, 
which become stronger on the posterior wing, each pair separated by a smaller inter- 
polated rib, the whole crossed by wavy, delicate, laminar frills, least conspicuous on the 
posterior wing. 
Obs. The present shell is believed to be Moore’s species (although he describes 
it as small) from the great expansion of the posterior wing, the absence of an anterior one, 
and the general resemblance to his figure. Tf not Moore’s species, it must be an 
undescribed form. The folded and crumpled anterior dorsal margin is a typical feature 
of a Maccoyella, and we thus have a very interesting morphological change from the 
shorter posterior wing of 2£. Sarhlyi to the lengthened condition of that portion of the 
shell in the present species. The subangular convexity of the umbonal region is also a 
marked feature ; and should this form prove distinct from iLT. suhstriafa, Moore, it may 
be called 31. suhanyularis. The above characters have been chiefly derived from a 
specimen in Mr. Sweet’s Collection. 
Loc. Bungeworgorai Creek, near Mount Abundance {Q. Sweet— GoWn. Sweet, 
Melbourne) ; Wollumbilla {The late Bcv. W.B. GlarTce). 
Genus — ATTOELLA, Eeyserling, 1846. 
(Reise in das Petschora-Laud, p. 297.) 
Gen. Char. “ Obliquely elongated, inequivalve, of thin structure, pearly within, 
and with concentric sulcations externally ; left valve strongly convex, with incurved 
beaks, a shortposterior and an almost obsoletoanteriorear,represented by a slight internal 
thickening; margin of shell in front below the beak insinuated; right valve flat or 
slightly convex near the umbo, with a small indistinct posterior and a still shorter 
anterior ear, generally a little twisted, and separated from the margin below by a deep 
byssal sinus ; hinge-line in both valves straight, short, and in the right valve usually 
with a small blunt tooth, ligament external, linear ; muscular scars small, posterior, 
submarginal, anterior placed near the ear, and often almost obsolete.” {Sfoliczh'a.) * 
Obs. Dr. Stoliezka’s description of this interesting genus is quoted, as being the 
best and most comprehensive with which I am acquainted; it is to all intents and 
purposes the same as the m’iginalby Von Keyserhng. 
By most authors is said to be a Jurassic genus, but Eichwald believes the 
rocks from which the original examples wore procured by Keyserling to be of Cretaceous 
age. Species deflnitcly known to be of this period have been described by Stoliezka, 
Gabb, Conrad, and others, and there now appears to be no doubt of its existence during 
the epoch in question. 
Aucblla iinGHETOENE>rsi.s, Etheridge, sp., PI. 25, figs. 1-6. 
Avicula hurjhendcnensis, Etheridge, Quart. Journ. Geol. .Soc., 1873, xxviii., Pt. 3, p. 346, t. 25, f. 3. 
Aucdla Liverudyei, Etheridge fih, Journ. E. Soc. N. S. Wjiles, for 1883 [1884], xvii., p. 90, Wd plate (top 
and lower right-hand figs.) 
Char. Obliquely sub-deltoid, very inequivalve, plano-convex. Left valve 
convex, inoceramiform, gibbous, and narrowed about the umbo, expanding ventrally • 
beak or umbo prominent and much incurved anteriorly, greatly overhanging the hinge- 
line ; anterior side vertical, the margin almost straight, and when seen from the inside 
deeply insinuated under the beak ; posterior side steep, obliquely expanding ; posterior 
ear and hinge margin very short ; ventral margin obliquely rounded ; surface with faint 
concentric undulations, which become more apparent and laminar towards the ventral 
margin. Eight valve gently convex or prominent about the umbonal region, flattened 
Pal. Indica (Cret. Fauna), 1871, iih, fa«c. .5.8, p. 390. 
