234 



PROC. COTTESWOLD CLUB vol. xiii. (4) 



I/'rt a. Bilobation directly, with- 

 out any definite prior 

 sulcation. 



Z. emargmata (incipient) ; Z. 

 biconiis (olim Z. emargmatu) ; 

 Z. buUata ; Z,. ohovata. 



Dorsal sulcation ; de- 

 veloping into a some- 

 what linguiform ventral 

 projection. 



Later bilobation, and the 

 fusion of the lobes below 

 the sulcus producing a 

 perforated shell. 



Glossot/iyris (Nucleatse.) 



Pygope. 



Ill- a. Flattening or slight de- 

 pression of dorsal valve. 



h. Develops into dorsal 

 sulcation. (J 



c. Later dorsal plication 

 within the sulcus. V^ 



T. Leesi ; T. simplex; T.omalo- 

 gaster ; T. sul'ontalogasfer, sp. n. 

 T. curvifrons. \ Aulacotliyris 



y Haasi 

 T. galeiformis. j follows this 



I plan. 



The T.-ciirvifrons series is quite distinct from Terebra/ula, the 

 method of biplication being just the opposite. Some of the series 

 have been put to Glossot/iyris ; but always with a query, as genetic 

 connexion therewith was obviously out of the question, though a 

 certain morphic similarity could be seen by anyone. The necessity 

 for a new generic name has long been felt ; and I venture to propose 

 Pseudoglossothyris (see p. 240.) 



IV a. Dorsal sulcation pro- 

 nounced, and even ex- 

 cessive in some cases. 

 b. Bilobation added to pro- 

 nounced dorsal sulca- 

 tion. 



Aulacothyris. 



Aulac. crejvkernioisis. 



IV« a. Dorsal sulcation pro- 

 nounced ; and later, 

 ventral sulcation pro- 

 ducing incipient biloba- 

 tion. 



Aulacothyris Mooni in some 



cases ; 



Aulac. bi sulcata, S. Buckm. 



