BRACHIOPODA. 
355 
Family BILLINGfSELLIBJE, Schuchert. 
Billingsella,* Hall, 1892. 
Family CLTTAMBONITIBJE, N. H. Wixchell and Schuchert. 
Protorthis, Hall, 1892. 
POLYTCECHIA, Hall, 1892. 
Clitambonites, Pander, 1830. 
Prnnites, Pander, 1830. 
Gonamhonites, Pander, 1830. 
Hemipronites, Pander, 1830. 
Orthisina, d’Orbigny, 1847. 
ScENiDiuM, Hall, 1860. 
Mystrophora, Kayser, 1871. 
Family STB,ICKLA]S[BmiIB^. 
Syntrophia, Hall, 1892. Stricklandinia, Billings, 1859. 
Family CAMARELLIBAB. 
Camarella, Billings, 1859. 
Parastrophia, Hall, 1893. 
Anastrophia, Hall, 1879. 
Brachymerus, Shaler, 1865. 
(?) Branconia, Gagel, 1890. 
PoRAMBONiTES, Pander, 1830. 
Isorhynchus, King, 1850. 
Noetlingia, Hall, 1892. 
Lycophoria, Lahusen, 1885. 
Camarophoria, King, 1846. 
Camarophorella, Hall, 1893. 
Family PENTAMERIB^E. 
CoNCHiDiUM, Linne, 1753. Sieberella, (Ehlert, 1887. 
Gypidia, Dalman, 1828. Capellinia, Hall, 1893. 
Antirhynchonella, Quenstedt, 1871. Pentamerella, Hall, 1867. 
Zdimir, Barrande, 1879. Gypidula, Hall, 1867. 
Pentamerus, Sowerby, 1813. Amphigenia, Hall, 1867. 
Barrandella, Hall, 1893. 
* The genus Billingsella, in correspondence with its early geological age, presents an elementary 
structural aspect indicating that it may have served as a point of departure for the Ortbid^ and 
Rtropboubbidje. 
