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 Encrimrus 

 ornatus. It was probably derived from the outcrops of the sandstone of the 

 Clinton group in Orleans county, or vicinity, New York. 



Genus ATRYPINA, gen. nov. 



PLATE Llir. 



1845. Terebratula, db Vkrneoil. Geol. de la. Russ. d'Europe et ;de8 Mont, de I'Oaral, p. 96, pi. x, 



figs. 14 a-e. 



1848. Tereibratula, Davidson. Bull. 8oc. Geol. de France, vol. v, second ser., p. 332. pi. ill, fig. 32. 



1862. Atrypa, Hall. Palzeontology of New York, vol. ii, p. 277, pi. Ivii, figs. 6 a-7». 



18.57. Leptoccdia, Hall. Tenth Ann. Rept. N. Y. State Cab. Nat. Hist., p. 108. 



1859. Leptocmlia, Hall. Palseontology of New York, vol. iii, p. 246, pi. xxxviii, figs. 8-12. 



1859. Shynchonella, Retzia, Salter. Murchison's Siluria, second ed., p. 2.50, fig. 6 ; p. 544. 



1860. Retzia, Limdstrom. Gotland's Brachiopoda, p. 337. 



1867. Retzia f Davidson. Bi-it. Siluiian Brachiopoda, p. 128, pi. xiii, figs. 10-13. 



1868. TVematogpira f Mkbk and Worthbn. Geol. Surv. Illinois, vol. iii, p. 381, pi. vii, fig 2. 



1879. Corfospira, Hall. Twenty-eighth Ann. Rept. N. Y. State Mas. Nat. Hist., p. 162,'pl. xxv, 



figs. 39-43. 

 1882. Calotpira, Hall. Eleventh Ann. Rept. State Geologist Indiana, p. 303, pi. xxv, figs. 39-43. 

 1882. Atrypa, Davidson. Brit. Silur. Brach., Snppl. p. 114, p. vii, figs. 7 a, b. 

 1889. Ccdospira, Bkbchbb and Clarkb. Mem. N. Y. State Mas., vol. 1, No. 1, p. 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 



