BRACHIOPODA. 189 



in it a nearer relationship to Rhynchotrema, than to the Silurian and Devonian 

 representatives of Camarotcechia ; in other words, the existence or absence of 

 the median brachial septum should be regarded as of less significance than the 

 co-existence of a similar type of hinge-structure. 



In exterior characters Stenoschisma formosa is a trihedral, strongly plicated 

 shell with well-developed fold and sinus, of an expression not uncommon 

 throughout the Devonian rhynchonellids. 



Genos camarotcechia, nom. nov. 



• PLATE LVII. 



1841. Atrypa, Conrad. Ann. Rept. Palaont. Dept. N. Y., p. 55. 



1843. Atrypa, Hall. Geology of New York j Rept. Fourth Dist. ; Tables of Organic Remains, No. 66, 



figs. 3, 4 ; No. 67, fig. 2. 

 1847. Atrypa, Hall. PalsBOntology of New York, vol. i, pp. 21, 23, pi. iv (bis), figs. 7, 9. 

 1852. Atrypa, Hall. Palaeontology of New York, vol. ii, p. 70, pi. xxiii, figs. 4, 5 ; p. 274, pi. Ivii, 



fig. 1 i p. 279, pi. Iviii, figs. 3, 4. 

 1857. RhywlumeHa, Hall. Tenth Ann. Rept. N. Y. State Cab. Nat. Hist., p. 78, figs. 1-7 ; p. 82, 



figs. 1-3 ; pp. 81, 86. 

 1860. RhynchoneUa, Billihob. Canadian Journal, vol. v, pp. 271, 272. 



1860. RhynchoneUa, Hall. Thirteenth Ann. Rept. N. Y. State Cab. Nat. Hist., pp. 87, 88. 

 1862. RhynchoneUa, A. Winchbll. Proc. Acad. Nat. Sci. Philadelphia, pp. 407, 408. 



1862. RhynchoneUa, BiLLiNas. Palseozoic Fossils, vol. i, pp. 141-143, figs 118-120. 



1863. RhynchoneUa, Hall. Transactions of the Albany Institute, vol. iv, pp. 215, 216. 



1867. Rliynehanella (Stenocisma), Hall. Palseontology of New York, vol. iv, pp. 335-345, 348-353, 



pi. liv, figs. 1-59; pi. liva, figs. 1-23, 44-49 ; pi. Iv, figs. 1-52. 

 1879. RhynchoneUa, Hall. Twenty-eighth Rept. N. Y. State Mus. Nat. Hist., pp. 163, 164, pi. xxvi, 



figs. 12-33. 

 1882. RhyncJumeUa, Hall. Eleventh Ann. Rept. State Geologist of Indiana, pp. 305-307, pi. xxvi, 



figs. 12-33. 

 1884. RhynchoneUa, Walcott. Monogr. U. S. Geol. Survey, vol. viii, p. 152, pi. xiv, fig. 3 ; pi. xv, 



fig. 6 ; p. 155, pi. xiv, fig. 8. 



1887. RhynchoneUa, Gossblbt. Annates de la Soci6t6 Geologique du Nord, vol. xiv, p. 188, 



pU. i-iii. 



1888. RhynchoneUa, Hbbbick. Bulletin Labor. Denison Univeraity, vol. iii, pp. 39, 40, pi. v, fig. 1 ; 



pi. vii, fig. 26 ; pi. x, fig. 9. 



By restricting the application of the term Stenoschisma to shells agreeing in 

 hinge-structure with RhynchoneUa formosa, the necessity is created for a new 

 designation for the large group of shells to which that term was applied in 

 1867.* While these shells are susceptible to considerable variation in exterior, 



* PalsBontology of New York, vol. iv. 



