Prohinnites trilinearis (Seeley, 1861)
SEELEY, H. 1861. Notes on Cambridge paleontology. I. Some new Upper Greensand bivalves. The Annals and Magazine of Natural History [Third Series], 7: 116-124, pls. 5, 6. [p. 119, pl. 6, fig. 2]
1861 Hinnites trilinearis Seeley, 1861
H. Seeley, 1861, plate 6.
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«Shell suborbicular; one valve flat, the other somewhat convex; both very thin and irregular. Ornamented with radiating ribs, which are closest on the flat valve. The ribs are ornamented with three longitudinal lines or keels, of which the middle one is generally the largest, and also with exceedingly close transverse strise, which, from their delicacy, are seldom preserved. On the convex side the ribs number from fifteen to about twenty, and have intervening spaces, more than twice their own width, which are quite smooth. On the flat side are some twenty-five or more ribs, which are slightly smaller than those of the other valve. The cast shows in the intermediate spaces indications of each having had two or three striae.
Small worn fragments of this species, which are not uncommon, may easily be mistaken for Pecten Beaveri, to which the shell, but for its irregular growth, would bear some resemblance. None of the specimens have the umbones perfect, or show trace of an ear.
Coll. University; J. Carter, Esq.; Mr. Farren, &c. A very marked variety occurs which has good claims to be considered a distinct species. It is distinguished by having all the ribs much closer and higher, and those of the convex side nearly as wide as the intervening spaces; it also commonly has a striation in each interspace, and as many as five wide folds on each rib. On the flat valve the folds on the ribs are very obscure; the interspaces commonly have a single strong striation, and appear to have been finely striated transversely. I have provisionally marked it Hinnites pectinatus. Rare. Coll. University ; J. Carter, Esq. Loc. Cambridge and Ashwell.» HARRY SEELEY, 1861
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