669 
“ Ohs. It is to be regretted that we have not a particle o£ the original shell 
wherewith to recognise the nature of the markings, or even the ventral margin to aid 
us in determining whether the inner edge Avas crenulated or plain ; externally the shell 
appears to have been smooth or delicately concentrically marked. The cast of the 
hinge-line is such as to prevent our determining any teeth below the junction of the 
two valves. 
“In outward form this shell much resembles Lucina {CodaMa) percrassa, StoL, 
from the Arrialoor G-roup (India) ; and the shell is nearly equal in length to that of 
this species, but not so high. The pallial line appears to be simple ; and the muscular 
impressions resemble those of Jdeciunculus. Some Axincea from the Indian Cretaceous 
rocks, but for their size, would very closely resemble this shell. "We possess one 
specimen only, and that a cast of one valve. 
Three similar casts have come under my own observation (PI. 27, fig. 1), but I 
am in no way better prepared to offer any definite suggestion as to their generic affinity 
than was Mr. Etheridge. Cardinal and lateral teeth were undoubtedly present, so that 
the supposed resemblance to Axinasa {Pectuncuhts) may be at once dismissed. The 
hinge characters, however, arc too ill-preserved to warrant us in a complete generic, 
reference, but, in all probability, these shells belong either to the Cyprinidro or Luei- 
nida'. Eor a true Oyprina, the umbones are too central, although slightly on the 
anterior side ; whilst the absence of crenulations along the ventral interior of the valves 
separates them at once from that section of CodaMa referred to by Mr. Etheridge. 
Prof. K. Martin has described a large shell, having much the appearance of our 
fossils, but with the shelly matter preserved, from the Tertiary Beds of Java. He 
provisionally refers it to Lucina.* 
Prof. J. D. Dana, again, has figured a similar form, referred to the same genus, 
from the Tertiary series of Oregon, under the name of Lucina acutilincata.'\ The 
Outline corresponds well with our shell. 
The almost central beaks, and nearly round outline, with an apparently indefinite 
or smooth surface ornament, are features of too marked a character to be easily passed 
over. The posterior muscular scar was large, deep, and round-oval, and the pallial sinus 
wide and open, and it is not impossible that we may here have the foreshadowing of a 
new genus. In two of the specimens one of the valves has been thrust upwards, 
producing an apparent inequality of the valves, but in the third they are normal. 
Loc. Maryborough {The late Jt. Laintree). 
Order— LUCINACEA. 
Family— LHCINID^. 
Genus — UNIOAPDIJJM, d' Orhigny, 1850. 
(Prod. Pal. Strat., i, p. 218.) 
UmcAHDiuM ? Ethebidgei, sp. nov., PI. 27, fig. 1. 
Genus?, Etheridge, Quart. Journ. Geol. Soc., 1872, xxviii., p. 339, 1. 19, f. 4. 
Sp. Char. Shell large, more or less semicircular, if anything slightly oval, the 
transverse measurement being slightly the greater, nearly equilateral, convex, and 
inflated in the umbonal region. Dorsal margin nearly straight, rounded at the lateral 
angles ; anterior and ventral margins rounded, but the posterior slightly produced. 
* Sammiungen Geol. Reiebs Mus. in Leiden, 1883, i.. No. 5, Heft 4, t. 13, f. 43. 
t Geology, Wilkes’ U. S. Explor. Exped., 1849, x., Atlas, t. 18, f. 2. 
