Bracuiopopa. | UPPER PALAXOZOIC MOLLUSCA. 461 
very regular concentric ridges, smaller and closer than those of the receiving valve (four punctured and four 
smooth bands in the space of two lines at four lines from the beak). Length seven lines, proportional width 
=, length of entering valve 4, depth of receiving valve =, depth of entering valve ;;. 
This species is intermediate in all its characters between Producta punctata and Producta fimbriata, but 
is perfectly distinct from both as a species: it agrees with the former in the xwmerous, instead of single rows of 
spinules on each concentric band, while it differs from it, and agrees with the P. imbriata, in the elongate-ovate 
form, absence of mesial furrow, and very great gibbosity of the receiving valve, differing however from it in the 
smaller size, greater number of concentric bands in a given space at the same distance from the beak, and in 
having several rows of minute punctures, instead of a single row of elongate tubercles on each band. M. de 
Koninck, without probably having seen the species, refers it to the young of P. punctata, but it is greatly more 
gibbous, has more angular transvere bands, which are very different from those of P. punctata by their very 
narrow punctured space on the rostral edge compared with the wide unpunctured portion, the reverse of what 
is seen in that species. 
Position and Locality Not uncommon in the dark carboniferous limestone of Lowick, Northumberland, 
and the similar limestone of Kendal, Westmoreland. 
Explanation of Figures.—P\. 3. H. fig. 4, entering valve natural size; fig. 4a, do. profile of receiving 
valve ; from the carboniferous limestone of Lowick, Northumberland ; fig. 46, do. front view ; fig. 4c, portion 
of surface magnified. 
PRODUCTA FIMBRIATA (S07.) 
Ref.—Id. Sow. Min. Con. t. 459. f. 1; de Koninck, Monog. Prod. t. 12. f. 3. 7 
Desc.—Longitudinally ovate; hinge-line slightly less than the width of the shell. Receiving valve very 
convex in the middle; profile greatly arched ; beak very large, prominent, and incurved below the hinge-line ; 
ears very small, flattened, obtuse-angled. Surface regularly traversed by concentric prominent bands, each be- 
coming obtusely angular in its middle towards the sides of the shell, and being throughout its rostral half 
fringed by a single row of elongate tubercles, each punctured at its distal extremity (about five in two lines in 
middle of shell) ; the anterior half of each band marked with fine, waving, concentric lines of growth (two bands 
occupy three lines at six lines from the beak). Entering yalve truncato-orbicular, gently and slightly concave, 
with regular concentric ridges (about four in three lines at six lines from the beak), on each of which is a single 
row of tubercles, more rounded than those of the receiving valve; no mesial furrow in either valve. Average 
length ten lines, proportional length of entering valve #4, width =, depth of receiving valve [, depth of entering 
valve +. 
There being but a single row of rather large spine-bases, instead of the numerous rows of minute spines 
and punctures on each concentric band, separates this species easily from P. punctata, and its great gibbosity 
from the P. laciniata (M°Coy); the small size, elongate form, fewer, and more distinct, spiniferous ridges 
with the tubercles only crossing half of their width, and their occurring on the sides as well as on the middle of 
the shell, separate it from P. pustulosa. 
Position and Locality —Abundant in the dark carboniferous limestone of Lowick, Northumberland ; in the 
similar limestone of Kendal, Westmoreland; common in the lower part of the carboniferous limestone of Derby- 
shire; carboniferous limestone of Poolwash, Isle of Man; carboniferous shale of Beith, Ayrshire. 
Propucta FLEMINGI (Sov.) 
Ref. and Syn. =(P. longispinus Sow. M. C. t. 68. f. 1+ P. Flemingi id. id. t, 68. f. 2+ P. lobatus id. id. t. 318. 
f.2 to 6+ P. sulcatus id. id. t. 819. f. 232+ P. costellata M°Coy, Syn. Carb. Foss. Irel. t. 20. f. 15+ [P. 
pugilis Phill. Geol. York. t. 8. f. 6=P. tubarius Keyserling, Reise in das Petschora Land, t. 4. f. 6]) = 
P. Flemingi de Koninck, Monog. Prod. t. 10. f. 2. 
Dese.—Subcylindrical, elongate, quadrangular; sides steep, nearly parallel; front flattened or slightly 
convex, usually a narrow mesial furrow, varying very much in strength, or sometimes absent, becoming obsolete 
