Bracuiopopa. | UPPER PALZOZOIC MOLLUSCA. 469 
the nearly straight front descends by an abrupt curve, nearly at right angles to the plane of the visceral disk, 
and is usually quite smooth, or with exceedingly delicate transverse lines of growth or minute longitudinal 
striae, when the thin shell is partially decorticated ; a very obscurely defined shallow mesial hollow extends from 
about four lines from the beak to the front margin; a few spine-bases on the ears near the hinge-line, Entering 
valve similar to the receiving one, but with a very short deflected front portion, leaving a large internal space 
between the valves, without much difference in curvature of the rostral portions. Width one inch four lines, 
50 
proportional length of visceral portion of either valve 3, length of deflected front of receiving valve 2, ditto 
of entering valve =. 
This species by its comparatively flattened, concentrically wrinkled visceral disk, and nearly smooth pro- 
duced front abruptly arched nearly at right angles, approaches a Leptagonia in appearance, but has no cardinal 
area. It is not likely to be confounded with any other species known. 
Position and Locality.—Rather rare in the grey or lower carboniferous limestone of Derbyshire. 
Propucta puncTAatTa (Mart. Sp.) 
Ref. and Syn. = Conch. Anomites punctatus Martin, Pet. Derb. t. 37. fig. 6 to 8. = Anomites thecarius Schlot. 
Nacht. Pet. Vol. I. t. 14. f..1.= Productus punctatus Sow. Min. Con. t. 323; id. id. de Koninck, Monog. 
Prod, t. 13. 
Desc.—Rotundato-quadrate ; hinge-line rather less than the width of the shell; receiving valve moderately 
gibbous; beak prominent, tumid, narrow, much incurved below the hinge-line; a shallow mesial sulcus extends 
from about six lines from the beak to the front margin. Entering valve flattened, slightly concave, with a slight, 
undefined mesial ridge corresponding to the hollow in the opposite valve, and reaching to about four lines from 
the beak; ears flattened, scarcely defined, obtuse; shell very thin. Surface of both valves concentrically 
marked by flat imbricating subregular bands of growth, varying from half a line to a line and half in width, 
each closely and variously punctured or marked with numerous rows of perforated spinulose bases of the 
very numerous, small, crowded, hair-like spines, which are extremely slender, commonly three or four lines long, 
the largest being situated near the posterior portion of each of the transverse bands, which are separated from 
each other by narrow, smooth, concentrically lined spaces on the most posterior part of each, Width about two 
a4 
inches three lines, proportional length =>, length of entering valve 4, depth 4, depth of entering valve 4. 
The transverse bands are narrower, more regular, and have rather fewer and larger spines on the entering 
valve ; there are commonly from twenty to twenty-four of these bands on average-sized specimens, the surface 
appearing as if closely punctured with a pin, when the little spines are broken off, as is usually the case. There 
are from two to three concentric bands in a space of two lines at six lines from the beak. M. de Koninck, in his 
beautiful monograph of Productus, refers my P. elegans and P. laciniata to this species, but, I am convinced, 
erroneously, as I have now seen many specimens of the former, and under that name in the present work I give 
descriptions and figures of the large, as well as of the small, valve which I only knew on the first publication. The 
P. elegans is more allied to P. fimbriata ; the P. laciniata is clearly distinguished by the characters I have 
already published, but it is to the P. fimbriata, and not P. punctata, which it is allied. 
Position and Locality—Common in the earboniferous limestone of Derbyshire ; not uncommon in the 
dark carboniferous limestone of Lowick, Northumberland; dark carboniferous limestone of Ronalds-way and 
Poolwash, Isle of Man ; red carboniferous limestone of Closeburn, Dumfriesshire ; dark carboniferous limestone 
of Dalmellington, Dumfriesshire. 
Propucta pustuLosa (Phiil.) 
Ref. and Syn.—ld. id. Geol. York. Vol. I. t. 7. f.15; id. de Koninck, Monog. Prod.t. 12. f. 4 a, b, ¢ (not 4d, 
nor t. 13. f. 1); t.16.f. 8 and 9.> P. pywidiformis de Koninck, Monog. Prod. t. 12. f. 1; t. 16. f. 2. 
Dese.—Rotundato-quadrate ; substance of the shell very thin; hinge-line nearly as wide as the shell, 
forming nearly rectangular flattened ears, strongly defined in the large valve. Receiving valve extremely gibbous, 
