1S6 PALEONTOLOGY OF NEW YORK. 



that the more fragile portions of the ribbon are lost, leaving only the umbonal 

 blades and the loop. 



The same details both of exterior and interior structure have been observed 

 in the species Ccelospira Camilla, Hall, of the Corniferous limestone of New York 

 and Canada, and, with the exception of the brachial apparatus, in the Atrypa 

 acutiplicata, Conrad, of the same fauna. It is clearly evident that the structure 

 in the species of Cojlospira here mentioned, is essentially the same as in 

 Anoplotheca venusta and A. {Bifida) lepida. The only material difference, that can 

 now be indicated between these forms, is one of greater geological than 

 biological significance; the later, or middle Devonian forms (Anoplotheca) 

 being more convex, more coarsely and sparsely plicated and more strongly 

 striated concentrically. Upon this basis of distinction the name C(elospira 

 may be retained with a subgeneric value. 



There are a few species in the Clinton fauna which have the outward expres- 

 sion of Ccelospira, and agree with it in the structure of the articulating appa- 

 ratus. These species are Atrypa plicatula, Hall, A. planoconvexa, Hall, and 

 A. hemispharica (Sowerby), Hall {= Leptocalia hemispherica, Davidson). The 

 brachidium in these forms is not yet known, and their reference to Ccelospira 

 is therefore provisional. 



Genus LEPTOCCELIA, Hall. 1859. 



PLATE Lin. 



1841. Atrypa, Coitbad. Qeol. Survey N. Y. ; Rept. Palseont. Dept., p. 66. 



1846. Atrypa, Morris and Sharps. Quart. Jour. Geol. Soc, vol. ii, p. 27B, pi. x, fig. 3. 



1856. Orthin, Sharpe and Salter. Trans. Geol. Society London, second ser., vol. vii, p. 203. 



1857. Leptocalia, Hall. Tenth Ann. Rept. N. Y. State Cab. Nat. History, p. 108. 



1859. Leptocadia, Hall. Palaeont. of N. Y., vol. iii, pp. 449-4.52, pi. ciii b, fiffs. 1 a-g ; pi. cvi, figs. 1 a-f. 

 1861. Ortliis, Raltkr. Quait. Jour. Geol. Society, vol. xvii, p. 68, pi. iv, fig. 14. 

 1868. Leptocadia, Mbbk and Wobthkn. Geol. Surv. Illinois, vol. iii, p. 397, pi. viii, figs. 3 a~c. 

 1892. Leptocalia, Ulrich. Palaozoische Verstein. aus Bolivien: Neues Jahrb. fUr Mineral., etc., 

 Beilagebnd. viii, p. 60, pi. iv, figs. 9 a, b, 10-13. 



The typical species of this group is L. flabellites, Conrad, of the Oriskany 

 sandstone; a shell which differs, as far as its structure is known, from Ccelospira 

 concava, only in its greater size and coarser, simple plication of the surface. In 

 general contour, structure of hinge, cardinal process, muscular scars and inter- 



