Bracuiopopa. | UPPER PALZXOZOIC MOLLUSCA. 417 
front margin “2, depth of ditto 4, depth of entering valve ;;,, of receiving valve ;,,; width of very large Irish 
specimen one inch five lines, proportional length of receiving valve 7, depth of both valves 5. 
Distinguished from the B. duplicicosta (Phill.) by the more longitudinally oval, depressed form, very short 
hinge-line, and cardinal area. 
Position and Locality —Not very uncommon in the carboniferous limestone of Derbyshire. 
Explanation of Figures.—PI. 8 D. fig. 25, profile natural size; fig. 25a, ditto same specimen, entering 
valve (the cardinal area seeming slightly too wide); fig. 25, ditto ditto receiving valve; fig. 25c, ditto ditto 
end view shewing the sinus in the front margin. 
SPIRIFERA GRANDICosTATA (M°Coy). Pl. 3. D. fig. 29. 
Ref—M Coy, Ann. Nat. Hist. 2nd Series, Vol. X. 
Desc.—Transversely subrhomboidal, sides abruptly attenuated and flattened, twice as wide as long, 
moderately convex ; hinge-line acute-angled, cardinal area broad, with parallel sides; profile of receiving valve 
abruptly arched to the incurved beak in the posterior third of its length, much more gently arched in the 
anterior two-thirds, so that the anterior lobe projects much from the front margin; mesial hollow deep, corre- 
sponding ridge moderately prominent ; radiating ridges very large, thick, angular, three strongly marked on the 
mesial hollow, of which the middle is much the broadest, and most depressed on the shell; the two lateral are 
imperfectly and obscurely triplicated towards the margin ; corresponding sulci on mesial ridge faintly marked ; 
on each side are about five great angular radiating ridges, some of which shew a faint tendency to imperfect 
division towards the margin; the narrow flattened sides, or cardinal angles, when preserved, shew five or six 
very much smaller obscure radiating ridges. Width about two inches six lines, proportional length of receiving 
45 8 
valye ;*, of entering valve 4, width of cardinal area ;;, depth of sinus in front margin ;5, depth of both 
valyes =. 
This is allied to the S. trigonalis of Martin, but differs from it by its abruptly narrowed and attenuated 
sides, and by its few very large angular ridges occupying the body of the shell, and the abrupt diminution in 
size of the five or six outer ridges on each side. A very young specimen, nine lines wide, has the three 
ridges in the mesial hollow distinctly marked, but nearly as large as the lateral ones, of which there are three or 
four great ones on each side, but scarcely a trace of any additional ones on the flattened cardinal angles, which 
are strongly striated parallel to the margins. 
Position and Locality——Rare in the carboniferous limestone of Derbyshire, (but common in the Irish 
limestone at Ardagh, from whence there are also good specimens in the collection.) 
Explanation of Figures —P\. 3. D. fig. 29, atural size receiving valve, the four or five ridges on each 
sideof the middle are not quite large enough to shew the abrupt change from them to the very small lateral 
ones; fig. 29a, ditto front view; fig. 29, ditto entering valve, the four or five ridges, next the middle, on 
each side not quite large enough. 
SPIRIFERA INScULPTA (Phill.) 
Ref. and Syn. =1d. id. Phill. Geol. York. t. 9. f. 2 and 3.=S. Koninckianus D’Orb. Prod. Pal. p. 149. 
S. crispus de Kon. (not of Lin.) Anim. Foss. Belg. t. 15. f. 8a, 5, ¢ (not d, ¢). 
Desc.—Entering valve nearly semicircular ; front and side margins regularly arched, very deeply plicated 
with large salient and re-entering angles, formed by the extremely large, angular, radiating ridges, and the equal 
deep, angular, intervening spaces ; one or two lateral ridges on each side of the mesial ridge in the entering valve, 
the mesial ridge being only slightly larger than the adjoining ones ; receiving valve semi-conical; cardinal area 
half as high as wide, triangular, only slightly curved; beak large, elevated, slightly incurved ; from its apex the 
surface slopes gradually to the margin; two very strong angular ridges bound the very deep angular mesial 
sulcus, usually one, or rarely two lateral ridges on each side; surface crossed with coarse, suberect, subregular, 
scaly laminze of growth, marked with coarse, rather distant punctures (under a lens of three quarters of an inch 
3H2 
