OF CONCHOLOGY. 145 



{A. sericea, S. and A.) This genua was properly characterized, 

 and is still in use. It hns fifteen years' precedence over Argiope, 

 Desl., which necessarily becomes a synonym of the next regu- 

 larly proposed generic name applied to this group. This is 

 Megathyris of D'Orbigny, 1847, which must therefore be 

 adopted. For information in regard to Savigny's genus, see 

 Thorell, Ann. and Mag. Nat. Hist. 1868, p. 190. 



Fig. 23. 



Fig. 23. Megathyris dfcollata, i, showing the apophyses. 



Type. Megathyris decoUata, Cheran., sp. fig. 22, 23. 

 Anomia decollata, Cheran., Con. Cab. viii, p. 96, pi. 78, fig. 

 705. 



This is Anomia detruncata, Gmel., +• Terehratnla deeoUata, 

 Desh., + T. aperta, Blainv., + T. dimidiata, Scacchi, + T. car- 

 dita, Risso, -f T. wna-antiqua, Risso, + Argiope decollata of 

 Dav., Rve., and most modern authors. 



As Chemnitz was not a binomial writer, it is probable that 

 his specific name ought to give place to that of Gmelin. 



Hah. Mediterranean, living ; fossil in the miocene of Gib- 

 raltar and pliocene of Calabria. 



Subgenus Cistella, Gray. 



Cistella, Gray, B. M. Cat. Jan. 1853, p. 114. 11. and A. 



Adams, Gen. Rec. Moll, ii, p. 581 (not Cistelia, Geoifr. 



and Fabr. Coleop.) 

 Zellania, Moore, Proc. Somerset Archfeol. and Nat. Hist. Soc. 



1854. Dav., Mem. Lin. Soc. Normandie 1856, p. 141, 



pi. vii (type, Z. Baridsoni, Moore, fig.-*. 43, 44). Chenu, 



Man. de Conchyl. ii, p. 210. 



Shell with a single median submarginal septum and bilobed 

 loop. Surface smooth, or radiately ribbed. Brachia inter- 

 rupted by the septum. 



