BRACHIOPODA. 187 



tive of R. cuneata has been regarded as a variety of the specific type, var. 

 Americana, Hall. It occurs sparingly in the Niagara fauna of New York, but 

 abounds at Waldron, Indiana, and is not uncommon in the dolomites of Illinois 

 and Wisconsin. In Great Britain, however, the species appeared earlier, being 

 found, according to Davidson, in the Lower Llandovery if not even in the 

 Upper Caradoc. 



Genus S T E N S C H I S M A, Conrad. 1839. 



PLATE LVI. 



1839. jS'tejcsciswa. Conrad. Second Ann. Rept. Palseont. Dept., p. f>9, 



1859. Rhynchonella, Hall. Palaeontology of New Yoi-k, vol. iii, p. 23t), jil. xxxv, figs, tin-.i/- 



1867. i^tenocisma, Hall. Palaeontology of New York, vol. iv, pp. 334, 335. 



Mr. Conrad, in speaking of the rocks and fossils of the State of New York, 

 in his Second Annual Report (p. 59), makes use of this term for shells, the 

 only representative of which specified by him, is "the common Silurian bivalve 

 Terehratula Schlotheimii, Von Buch." The T. Schlolheimi is a well-known Per- 

 mian, not Silurian species, and some writers, notably Dr. CEhlert in Fischer's 

 Manuel de Conchyliologie, have considered it necessary to apply tlie term 

 Stenoschisma (Stenoscisma as written by Conrad) in accordance with the 

 characters of von Buch's species, which renders it equivalent to King's genus, 

 Camarophoria (1845). It is important in such a matter to get as near as 

 possible to Mr. Conrad's intentions ; that he was at a disadvantage in draw- 

 ing comparisons or making identifications of American with European 

 species is evident from his characterization of T. Schlotheimi ;is a " common 

 Silurian bivalve." 



Unquestionably he had before him at the time, and intended by this designa- 

 tion some New York species, and in Volume IV of the Palaeontology of New 

 York (p. 334) the author states that Mr. Conrad had used this name on a lith- 

 ographed but unpublished plate of the fossils of the Lower Helderberg group, 

 to designate a species subsequently described* as Rhynchonella formosa, Hall. 

 This is as close an approximation to Mr. Conrad's conception as is now possible 



* Palaeontology of New York, vol. iii, p. 236. 



