271 
independently, or as arising from the passage of concentric laminee, it is impossible io 
say. It is, of course, conceivable that this may represent a distinct species resembling 
very closely the British P. papyraceus. 
Loo. and Horizon. Eockhampton District* (0. W. I>e Vis; Colin. De Vis) — 
Gympio Beds. 
Order— MYTILACEA. 
Eamily — AVICTJLTDEil. 
Genus^MVBISMOPTEBIA,^ yen. nov. 
Gen. Char. Pteronitiform in appearance, the anterior end lobe-like and well 
developed ; posterior end alo.te. Area excavated along the cardinal edge of both valves, 
and deeply ridged for the reception of a ligament; cardinal teeth wanting, but a strong 
clavicle descends in each valve before the anterior adductor muscles ; one or more lateral 
teeth in each valve. Anterior muscular scars double and strong, the superior scar situated 
towards the umboues. External ornament of concentric ridges. 
Ohs. Those acquainted with Pterinea will at once perceive that the shell so 
generally known to Australian Paheontologi.sts as Pterinea macroptera cannot properly 
be referred to that genus, from the character of its hinge. In Pterinea there are well- 
defined cardinal teeth, anterior in position to the uinbones, and one or more posterior, 
lateral, oblique teeth, besides a striated or grooved hinge-margin, and a well-developed 
posterior muscular scar. In the proposed new genus, there are no cardinal teeth proper, 
one lateral tooth only, either oblique or horizontal, and, further, the posterior scar is 
very indistinctly developed. But, proceeding from the cardinal margin, and anterior to, 
and bounding the anterior scar, is a very strong clavicle or crest, leaving very deep slits 
in casts. Herein the structure of this shell differs very widely from that of Pterinea. 
The hinge area of each valve is large, high, and coarsely ridged, and when the valves are 
in apposition, forming a deep angular and elongated depression, which, during life, must 
have been filled by a strong and powerful ligament. 
These features are particularly well shown in Morris’s figure of P . macroptera., 
especially the clavicle and the posterior lateral tooth. In Prof. De Koninck s figure, on 
the other hand, the anterior scar is placed before the clavicle, a very erroneous repre- 
sentation, as it succeeds immediately after it, and is supplemented by a very prominent, 
but at the same time smaller scar above it towards the umbones, but still not within 
the beak cavity ; this scar is not shown in De Koninck’s figure at all. 
Type. Pterinea macroptera, Morris. 
Meetsmoptbeia maceopteea, Morris, sp. 
Pterinea nmernptera, Morris in Strzeleoki’s Phys. Desorip. N. S. Wales, &;c., 1845, p. 270, t. 13, f. 1 and 2. 
,5 De Koninck, Foss. Fal. Nouv.-Gallcs du Snd, 18n, Pt. 3, p. 30-5. 
„ „ Etheridge fil., Proc. R. Phys. Soc. Edinb., 1S80, v., p. 298. 
Ohs. My Colleague has obtained a Pterinea, clearly this species, but only one 
specimen, and that without a part of the posterior wing. The small anterior lobe is 
only partially preserved ; the hinge-line was clearly somewhat less than the width of 
the shell; and there are distinct remains of concentric laminie, although the specimen 
is only a cast. The cast of one of the characteristic teeth is also preserved. 
Loc. and Horizon. Coral Creek, below Sonoma Eoad-crossing, Bowen Kiver 
(«. L. Jhcyfc)— in decomposed uodular ironstone of the Middle or Marine Series of the 
t^owen River Coal Eield. ' 
* See note, p. 199. 
.(■ pepurpoi = a partition. 
