ABA BRITISH PALZZOZOIC FOSSILS. {Bracutoropa. 
foramen and pseudo-deltidium wide. Width eleven lines, proportional width of visceral disk i, length of 
visceral disk of receiving valve , length of front *, space between the valves jj. 
This species is easily distinguished from L. analoga by the deep, wide, longitudinal mesial hollow, giving 
it a strong resemblance to the Producta plicatilis, from which it differs in its coarse longitudinal sulcation ; the 
resemblance however to the Producta Giriffithi of de Koninck is so great, that but for the known accuracy of 
that observer, we might suppose the cardinal area had been overlooked in that species, the more so as I observe 
in our specimens traces of the spinose tubercles, represented between the body of the shell and the ears in 
P. Grifithi, but not alluded to in his description of the present fossil. 
Position and Locality—Rare in the carboniferous limestone of Derbyshire. 
Subgenus. CHONETES. See page 249. 
Lert@NaA (Chonetes) crassistRIA (M’Coy). Pl. 3. H. fig. 5. 
Ref. and Syn. = Lepteena id. M*Coy, Syn. Carb. Foss. Irel. t. 20. f. 10. 
Dese—Nearly semicircular, middle portion of the shell subhemispherical ; greatest depth nearly at middle, 
of length, from whence the surface gradually slopes towards the front and sides, arching more rapidly towards 
the broad beak, which scarcely projects beyond the hinge-line; hinge-line exceeding the width of the shell, 
forming narrow, rounded, very slightly convex ears; about five slender tubular spines on the hinge-line on each 
side of the beak. Surface longitudinally fluted by about twenty-four coarse, slightly rugged, equal, sharply- 
defined, rounded, very prominent, simple ridges, five in two lines at four lines from the beak, marked by coarse 
transverse lines; intervening sulci very deep, concave, and about equalling the ridges in width; the ears are 
nearly destitute of ridges. Width eight lines, proportional length ;7,, depth =. 
The comparatively few and perfectly simple or unbranched ridges easily separate this species from my 
L. suleata and L. gibberula, with which M. de Koninck united it in his Monograph on the genus. It is 
in fact the most strongly marked species of the genus, and cannot be confounded with any other. 
In my original figure there seem, unfortunately, a few ridges too many, and owing to this erroneous 
crowding, their curious simplicity is not sufficiently apparent. Here and there on the ridges towards the 
margin may be observed some minute tubercular spines, resembling those alluded to by M. d’Orbigny in his 
Leptena variolata, in the Paleontological part of his Voyage dans Amérique Méridionale, and where absent 
they leave rather distant, small, scattered, broken pits, too few and far apart however to form a marginal band, 
or other marked feature, being besides only visible with a lens. 
Position and Locality —Rare in the carboniferous limestone of Derbyshire. 
Explanation of Figure.—P). 3. H. fig. 5, natural size, receiving valve ; fig. 5 a, portion of surface magnified. 
LeptmNna (Chonetes) HArpRENSIS (Phill. Sp.) 
Ref. and Syn. = Orthis Hardrensis Phill. Pal. Foss. t. 58. f. 104%, 6, c, d, not a, and t. 60. f. 104*. 
M. V. K. Geol. Rep. t. 15. f. 10; de Kon. Monog. Chonetes, t. 20. f. 2. 
Desc.—Subsemicireular, depressed; hinge-line slightly exceeding the width of the shell, forming pointed 
cardinal angles. Receiving valve gently convex in the middle, passing gradually into the flattened ears; side 
margins very slightly sigmoid ; front wide, widely convex, or flattened, or even slightly concave, in which latter 
case a wide, shallow, obscurely marked, mesial depression extends nearly to the beak. Surface radiated with 
rather coarse, slightly unequal, subangular ridges, all of which either branch, or receive fresh ridges of nearly 
the same size, at two or three perfectly irregular distances, between the beak and the margin ; the ridges often 
shew under the lens scattered, rather distant, ovate punctures, resembling spine bases; intervening angular 
sulci narrower than the ridges, often coarsely punctured ; ridges nearly equal on all parts of the shell, averaging 
twenty in two lines at three lines from the beak ; four or five slender spines on each side of the beak on the edge 
of the hinge-line, directed obliquely outwards and backwards, and having a smooth space, as wide as three or 
four strize between them; in some specimens towards the margin the striz are slightly rugose ; substance of 
. 
