142 
PALEONTOLOGY OF NEW YORK. 
shell allied to Leptocodia Jiahellites in the structure of its cardinal process and 
articulating apparatus, having, however, a highly convex brachial valve with a 
median septum extending one-half its length, two short, abruptly ending 
plications on the low median fold, upturned anterior margins, and explanate 
cardinal extremities. As far as the structure of its type species, Anahaia Paraia, 
Clarke, is known, it appears to be the precursor of the Devonian shells referred 
to Anoplotheca and Leptoccelia. 
Genus NUCLEOSPIRA, Hall. 1859. 
PLATE XLVIII. 
1843. Atrypa, Hall. Geology of N. Y.; Kept. Fourth Dist., p. 200, fig. 3. 
1852. Orthis, Hall. Palaeontology of N. Y., vol. ii, j). 250, pi. Hi, fig. 1. 
1857. Spirifer, Hall. Tenth Kept. N Y. State Cab. Nat. Hist., p. 57. 
1859. Nudeospira, Hall. Twelfth Kept. N. Y. State Cab. Nat. Hist., pp. 24-26. 
1859. Nudeospira, Hall. Palaeontology of N. Y., vol. Hi, jip. 219-223, pi. xiv, fig. 1 ; pi. xxviii, b, 
figs. 2-19. 
1860. Nudeospira, White. Jour. Boston Soc. Nat. Hist., vol. viii, p. 227. 
1863. Nudeospira, Hall. Transactions of the Albany Institute, vol. iv, p. 226. 
1867. Nudeospira, Hall. Palaeontology of N. Y., vol. iv, pp. 278, 279, pi. xlv, figs. 33-57. 
1879. Nudeospira, Hall. Twenty-eighth Kept. N. Y. State Mus. Nat. Hist., p. 160, pi. xxv, figs. 22-28. 
1882. Nudeospira, Hall. Eleventh Kept. State Geologist of Indiana, p. 301, pi. xxv, figs. 22-28. 
1882. Nudeospira, Whitfielp. Annals N. Y. Acad. Sciences, vol. ii, p. 194. 
1884. Nudeospira, Walcott. Monogr. U. S. Geol. Survey, vol. viii, p. 147. 
1889. Nudeospira, Nettblroth. Kentucky Fossil Shells, pp. 103, 104, pi. xxxii, figs. 1-4 ; jil. xxxiii, 
figs. 7-9. 
Diagnosis. Shells usually small, subcircular in outline. Valves subequally 
convex, often gibbous or ventricose. Hinge-line very short, cardinal ex¬ 
tremities rounded. On the pedicle-valve the cardinal area is low and 
obscured by the incurvature of the beak. Only in very young specimens 
is the deltidium exposed, and it then consists of two plates attached to 
the lateral margins of the delthyrium; in mature individuals these plates 
are coalesced and incurved, the median suture is lost and the foramen 
covered; the appearance of the deltidium is that of a triangular concave plate, 
limited by rather sharp dental ridges and covering the delthyrium for about half 
its length. The teeth are prominent, approximate, recurved at their tips, sup¬ 
ported by thickened bases but not by lamellae. Dental sockets very narrow. 
The muscular area is flabellate and extends for nearly one-half the length of 
