70 
PALEONTOLOGY OF NEW YORK. 
MERISTA, SuESs. 1851. 
PLATE XLVI. 
1851. Merista, Subss. Brachiopoden der Koessener Schichten, p, 17, pi. i. 
1851. Merista, Subss. Jahrb. der k. k. g-eolog. Reichsanst, vol, iv, p. 150. 
1856. Mei'ista, Subss. Classification der Brachiopoden von Th. Davidson, p. 85, pi. iii, figs. 18-20. 
1859. Camarium, Hall. Palaeontology of N. Y., vol, iii, pp. 486-488, pi. xcv, figs. 2-6. 
1859. Camarium, Hall. Twelfth Kept. N Y. State Cab. Nat. Hist., i?. 42. 
1860. Merista, Hall. Thirteenth Kept. N. Y. State Cab. Nat. Hist., j)p. 73, 93, figs. 10-13. 
1862. Camarium, Hall. Fifieenth Kept. N. Y. State Cab. Nat. Hist., pp. 176, 181, figs. 10-13. 
1867. Merista, Hall. Twentieth Kept. N. Y. State Cab. Nat. Hist., p. 258. 
1881. Merista, Davidson. Geological Magazine, new series, vol. viii, p. 289. 
1882. MeHsta, Davidson. British Silurian Brachiopoda, Supplement, p. 103, pi. v, figs. 10-13. 
Diagnosis. Shells transverse or elongate, both valves generally inflated; 
anterior margin sinuate, producing a fold and sinus on the marginal portion of 
the brachial and pedicle-valves respectively. 
In the pedicle-valve the apex is perforated by a circular foramen, which, 
however, is usually concealed at maturity, by the incurvature of the beak; 
deltidial plates rarely retained. On the interior the teeth are prominent and 
are supported by dental plates which extend either for a short distance into 
the interior cavity or are considerably produced at their bases as thickened 
ridges. Between the dental plates is an arched free plate (the “ shoe-lifter ” 
process) attached by its posterior and lateral margins, but at its anterior mar¬ 
gin extending beyond the dental lamellae and rising in a low, broad curve. In 
rare instances this process, from its origin, bears a sharp median carina which 
makes the anterior margin highly angulate. The muscular area appears to be 
limited to the space between the dental lamellae and to the surface of the 
“ shoe-lifter.” 
In the brachial valve a median septum is more or less strongly developed,* and 
divides a simple ovate adductor impression. The hinge-plate is short and deeply 
divided by a median groove. The brachial supports consist of spiral cones 
with their bases in apposition and parallel to the axial plane of the shell, and 
* In the figures of Merista JiarcuXea, Barrande, the type-species, given by Mr. Davidson (Supplement 
Biitish Silurian Bi-achiopoda, jd. v, figs. 10, 13), no evidence is seen of this dorsal septum; it appears, how¬ 
ever, in Barrandb’s figures, both of this species and of M. 'passm', Barrande (SystSme Silurien, vol. v, 
pis. X, xiii, xiv), and in American species of this genus. 
