388 BRITISH PALAXOZOIC FOSSILS. [Bracutopopa. 
the rostral tooth is a deep pit for the cardinal tooth of the opposite valve; reniform impressions rather large, 
the outer edge prominent, commencing near the beak, gradually arching forwards and outwards on each side, 
then turning abruptly backwards for about half their length, and finally turning horizontally inwards to meet 
each other near the apex of the mesial septum; at their posterior origin two small, ovate, prominent bosses 
(insertions of adductor muscles) close to the mesial septum. 
The hinge-teeth of the large valve, cardinal area, and pseudo-deltidium, totally remove this genus from 
Productus ; and 1 have not seen (nor does Professor King mention) any trace of the dendritic impressions of that 
genus ; but I do not think there is any difference between the reniform impressions and those either of Producta 
gigantea or Leptena transversalis. The group presents scarcely any difference from Leptena proper except its 
tubuliferous surface, and should be placed as a subgenus thereof. 
Lept@NA (Strophalosia) CAPERATA (Sow. Sp.) 
Ref. and Syn. = Leptena caperata Sow. Geol. Trans. 2nd Series, Vol. V. t. 53. f. 4. + L. membranacea Phill. 
Pal. Foss. f. 101 a, 6, and M. V. K. Geol. Russ. t. 15. f. lla, 6. 
Sp. Ch.—Semielliptical, moderately and evenly convex, except towards the cardinal angles, which are 
gradually flattened, and rectangular or slightly produced into very small acute points; cardinal area triangular, 
about one and a half lines high in specimen one inch three lines long in the receiving valve, narrow, and nearly 
parallel-sided in entering valve ; triangular foramen rather wider than long; entering valve nearly flat, with a 
mesial septum reaching rather more than halfway towards the front margin; entire surface of both valves 
covered with very small, close, round, subequal, undulated or zigzag, concentric wrinkles (about seven or 
eight in two lines at six lines from the beak), and numerous elongate, quincuncially arranged, spine tubercles, 
the latter often nearly obsolete, or when strongly marked obscuring the zigzag wrinkles, which appear stronger 
and straighter on the ears; often five or six long slender spines on the hinge-line. Width of adults one inch 
90 
two lines, proportional length =, depth of receiving valve ;;;, of entering valve about ;7,. 
All the specimens which I have examined of this species, named by Mr Sowerby himself, were certainly, 
specifically identical with the LZ. membranacea of Phillips; and I may observe, that it is only the entering valve 
of typical examples of that species that are nearly flat. The species varies greatly in the proportional strength 
of the two kinds of ornament, and when the beautiful concentric zigzag wrinkling is very strongly marked, the 
elongate tubercles can scarcely be seen; and on the other hand, when the quincuncial spine tubercles are 
strongly marked, the transverse wrinkling cannot be so distinctly seen; and this has perhaps given rise 
to the two species with Mr Phillips, although, from examination of Sowerby’s types and numerous specimens 
on the spot when they were first found, and where they abound, I readily traced every gradation between the 
supposed different types. None of the published figures do justice to the singular beauty and regularity 
of the minute, transverse wrinkling. 
Position and Locality.— Extremely abundant both in the slate and subordinate limestone of S. Petherwin. 
The var. approaching Producta scabricula in appearance, is not uncommon in the Upper Devonian slate 
in road quarry quarter of a mile S. of Marwood, also in the fine Upper Devonian grits at Parnstaple. 
LepTmNaA (Strophalosia) SUBACULEATA (JMurch.) 
Ref. and Syn. = 1d. Murchison, Bull. Geol. Soc. de France, Vol. XI. t. 11. f. 9, and Koninck, Monogr. Prod. 
t. 16. f. 4. = Leptena Fragaria Sow. Geol. Trans. 2nd Series, Vol. V. t. 54. f. 3, and t. 56. f. 5 and 6. 
Sp. Ch.—Subhemispherical or slightly quadrate; receiving valve very gibbous, with a rather narrow 
prominent beak ; hinge-line rather less than the width of the shell; ears gradually flattened, obtuse-angled ;_ car- 
dinal area and foramen very small; front margin wide, gently convex, no mesial depression; surface with 
numerous, rather large, irregularly scattered, round, or slightly elongate tubercles, each bearing at its apex a 
minute spine perpendicular to the surface ; surface otherwise either perfectly smooth or marked with obsolete, 
