BRACHIOPODA. 
161 
cordial and influential interest in the study of the fossils of the State of New 
York this generic name is proposed. This small block was virtually com¬ 
posed of the shells of this fossil with a few specimens of an undescribed 
Atrypina (A. Clintoni, sp. nov.) and fragments of the trilobite Encrinurus 
ornatus. It was probably derived from the outcrops of the sandstone of the 
Clinton group in Orleans county, or vicinity, New York. 
Genus ATRYPIN A, gen. nov. 
PLATE LIII. 
1845. Terehratula, db Vernedil. Geol. de la. Russ. d’Europe et 'des Mont, de I’Oural, p. 96, pi. x, 
figs. 14 a-e. 
1848. Terehratula, Davidson. Bull. Soc. Geol. de France, vol. v, second ser., p. 332. pi. ill, fig. 32. 
1852. Atrypa, Hall. Palaeontology of New York, vol. ii, p. 277, pi. Ivii, figs. 6 
1857. Leptoccelia, Hall. Tenth Ann. Kept. N. Y. State Cab. Nat. Hist., 108. 
1859. Leptoccelia, Hall. Palaeontology of New York, vol. iii, p. 246, pi. xxxviii, figs. 8-12. 
1859. Rhynchonella, Retzia, Salter. Murchison’s Siluria, second ed., p. 250, fig. 6 ; p. 544. 
1860. Retzia, Lindstrom. Gotland’s Bi'achiopoda, p. 337. 
1867. Retzia. ? Davidson. Brit. Silurian Brachiopoda, p. 128, pi. xiii, figs. 10-13. 
1868. Trematospira ? Meek and Worthen. Geol. Surv. Illinois, vol. iii, p. 381, jil. vii, fig 2. 
1879. Coelospira, Hall. Twenty-eighth Ann. Kept. N. Y. State Mus. Nat. Hist., p. ‘162,“pi. xxv, 
figs. 39-43. 
1882. Coelospira, Hall. Eleventh Ann. Kept. State Geologist Indiana, p. 303, pi. xxv, figs. 39-43. 
1882. Atrypa, Davidson. Brit. Silur. Brach., Suppl. p. 114, xi. vii, figs. 7 a, b. 
1889. Coelospira, Beecher and Clarke. Mem. N. Y. State Mus., vol. 1, No. 1, xi. 64, pi. v, figs. 17-23. 
Diagnosis. Shells small, subovate or subcircular in marginal outline, 
piano-, or subconcavo-convex in contour; surface coarsely and sparsely 
plicated. 
Pedicle-valve with the umbo prominent, the beak abruptly acute and more 
or less incurved. Foramen apical, and deltidial plates normally developed. 
The cardinal margins of the valve are somewhat extended in the typical 
species, though the hinge itself is quite short. Teeth divergent and unsup¬ 
ported, taking their origin on the lateral cardinal slopes, and very slightly 
recurved. Muscular scars exceedingly faint; no internal septa observ¬ 
able. 
Brachial valve with the cardinal process small, consisting of two short 
lobes, which meet at their apices, not extending back of the hinge-line, 
and diverging anteriorly. The surface of each lobe may be longitudinally 
