SCHlCHEnX. 



CLASSIFICATION OF TP^LOTREMATA. 



125 



la. Subfamily Megathyrin^ Dall, 1870 (emend Beecher, 1893). 



Arjiiopidir King, 18r)0; Megatbyrida^ ffihlert, 1887; Argiopida- Davidson, 1884 ; Argi- 



opinii' Davidson, 1887. 



Tt'iebiati'llidii' in wliicli the "loop is composed of desceiidiuji' brauclies 

 only, passing iu the liigliest genus through stages correlative with 

 (Jwyiiia, Cistella, and Megatliyris. The lower genera do not coniplete 

 the series" (Beecher), The original stock for the two following sub- 

 lamilies: 



Megathyris d'Orbigny, 1847. 



Argiopo Deslougcbamps, 1842 (not 

 Savigny and Audouiu, 1827). 

 Zellauia JNIoore, 1854. 



Gwynia King, 1850. 

 Cistella Gray, 1850. 



la"*. Subfamily Dallin^ Beecher, 1893.' 



Platidiiua? Dall, 1870. 



Terebratellidne with the " loop composed of descending and ascend- 

 ing lamella', passing in the highest genera through metamorphoses 

 comparable to the adult structure of Platidia, Ismenia, Miihlfeldtia, 

 Terebratalia, and Dallina. The lower genera, therefore, do not pro- 

 gress to the Hual stages" (Beecher). liecent genera restricted to 

 boreal seas. 



Dallina Beecher, 1893. 

 IMacandrevia King, 1859. 

 Terebratalia Beecher, 1893. 

 Lacqueus Dall, 1870. 



Freuula Dall, 1871. 

 Frenulina Dall, 1895. 

 Miihlfeldtia Bayle, 1880. 



Megerlia King, 1850 (not Robineaii 

 Desvoidy, 1830). 

 Platidia Costa, 1852. 



Morrisia Davidson, 1852. 

 Ismenia King, 1850 (not Dall, 



1871). 

 Kiugena Davidson, 1852. 



Kingia Scboenbach, 1867. 



Trigonosemus Koenig, 1825, 

 Fissurirostra d"( >rbigny, 1847. 

 Fissirostra d'Orbigny, 1847. 

 Delthyridea King, 1850, 



Lyra Cumberland, 1816. 



Terebrirostra d'Orbigny, 1847, 



Eudesia King, 1850. 



Ortbotoma Qiienstedt, 1871. 

 Trigonella Quenstedt, 1871. 

 Flabellothyris Deslougcbamps, 1884. 



Zeilleria Bayle, 1878. 

 Fimbriothyris Deslongchamps, 



1884. 

 Microthyris Deslongchamps, 1884. 



Oruitbella Deslongcbaraps, 1884. 

 Aulacothyris Douville, 1880. 

 Camerothyris Bittner, 1890. 

 Epicyrta Deslongchamps, 1884. 

 Cincta Quenstedt, 1871. 

 Antiptychina Zittel, 1883. 

 Plesiothyris Douville, 1880. 

 !Hynniphoria Suess, 1858. 

 ?Cruratula Bittner, 1890. 

 ?Orthoidea Friren, 1875. 



• Since many of the fossil genera liere referred to this family have not been studied in the light of 

 Beecher's and Oihlert's recent researches, it is not known that all belong to this boreal stock. 



