BRITISH SILURIAN BRACHIOPODA. 



79 



palgeontologists,^ but it seems undesirable and unnecessary to multiply their number ; 

 and I therefore propose to distribute the twenty-five or twenty-eight genera we are 

 provisionally disposed to record into the following four families: — I. Spiriferid^e ; 

 2. NucLEospiRiD^ ; 3. AthyridzE ; 4. Atrypid^ ; and I will now review each of 

 them separately, previous to describing in detail those that occur in our British 

 Silurian rocks. It must be borne in mind that it is not sufficient to know that a 

 Brachiopod is possessed of spiral appendages, to be able to determine its genus, but we 

 must be acquainted with its attachments and loop. 



1 Dall, in the ' Bulletin of 

 arrangement of the spiral-bearing 

 Family — AtrypiDjE. 

 Atrypa, Dalman. 



Spirigerina, d'Orbigny. 



Cleiothyris, Phillips. 



Cleidothyris, Paetel. 



Cliothyris, Agassiz. 

 Anoplotheca, Sandberger. 

 Zygospira, Hall. 



Stenocisma, Hall, 1877, 

 not Conrad. 

 ? CcElospira, Hall. 



Leptocoelia, Hall, 1857. 

 Koninckina, Suess. 



Koninckia, Woodward. 

 ? Davidsonia, Bouchard. 



Family — Spirifehid.'e. 

 Athyris, M'Coy. 



Athyris, Dav., 18.56. 



Seminula, M'Coy, 1844. 



Actinoconchus, M'Coy. 



Semiluna, King. 



Cleiothyris, King. 



Spirigera, d'Orbiguy. 



the United States National 

 Brachiopoda (synonyms being 



Euthyris, Quenstedt. 



? Charionella, Billings. 

 Merista, Suess. 



Camarium, Hall. 

 Pentagonia, Coz. 



Gonioccelia, Hall. 

 Meristella, Hall, 1861. 



Athyris, Dav., 1853. 

 — Billings. 

 ? Meristina, Hall. 

 Nucleospira, Hall. 

 Eetzia, King. 



Retzia, Davidson. 



Rhynchospira, Hall. 

 Trematospira, Hall. 

 Acambona, White. 



Eumetria, Hall. 

 Uncites, Befrance. 



TJncinites, Auct. 

 Spirifer, Sowerby. 



Spirifera, J. de C. Sow. 



Spiriferus, Blainville. 



Spirifer, Eafinesque. 



Museum,' 1877, proposes the following 

 printed in italics) : 



Hysterolithus, Quenstedt. 



Fusella, M'Coy. 



Choristites, Fischer. 

 — Quenstedt. 



Choristides, Keferstein. 



Delthyris, Dalman. 



Brachythyris, M'Coy. 



Trigonotreta, Konig ; Meek. 



Trigonotreta, Keferstein. 



Reticularia, M'Coy. 

 Martinia, M'Coy. 



Ambocoelia, Hall. 



Ambocoilia, Quenstedt. 

 Syringothyris, Winchell. 



iSpm/er, King ; Meek. 

 Cyrtia, Dalman. 



Cyrthm, d'Orbigny. 

 Cyrtina, I)av. 



Cyrtcena, Hall. 

 1 Mentzelia, Quenstedt. 

 Siiessia, Deslong. 

 Spiriferina, d'Orb. 

 ? Skenidium, Hall.'^ 



^ This last is not a spiral-bearing Brachiopod. 



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