BRACHIOPODA. 355 



Family BILLINGSBLLID^. Schucheht. 

 BiLLINGSELLA,* Hall, 1892. 



Family CLITAMBONITID.Ti, N. II. Wi.vchell and Sciicciibrt. 



Protorthis, Hall, 1892. Hemipronites, Pander, 1830. 



PoLYTCECHiA, Hall, 1892. Orthisina, d'Orbigny, 1847. 



Clitambonites, Pander, 1830. Scenidium, Hall, 1860. 



Prnnites, Pandei-, 1830. Mystrophora, Kayser, 1871. 



Gonambonites, Pander, 1830. 



Family ^^TRICKLANDINIID^. 



Stntrophia, Hall, 1892. Stricklandinia, Billings, 1859. 



Family CAMARELLID^.. 



Camarella, Billings, 1859. Porambonites, Pander, 1830. 



Parastrophia, Hall, 1893. Isorhynchus, King, 1850. 



Anastrophia, Hall, 1879. Noetlingia, Hall, 1892. 



Brachymerus, Shaler, 1865. Lycophoria, Laliusen, 1885. 



(?) Branconia, Gagel, 1890. Camarophoria, King, 1846. 



Camarophorella, Hall, 1893. 



Family PENTAMERID^f:. 



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 geniis Billingsella, in correspondence with its early geological age, present.s an elementary 

 structural aspect indicating that it may have served as a point of departui-e for the Obthidm and 

 Stbophomesid^. 



