370 MAZATLAN UNIVALVES 



Tablet 1730 contains a fragment, intermediate in form be- 

 tween PA. mutans and ? Chry sallida clausiliformis, remarkable 

 for the sudden transition, after 4 whirls, from a perfectly 

 smooth to a highly sculptured surface. The smooth part 

 measures '045 by '023. 

 Sab. Mazatlan ; 1 sp. off Spondylus ; Upool Col. 



433. ??ALABA , sp. ind. (a.) 



Tablet 1731 contains a fragment of a somewhat large shell ; 

 the first four whirls swelling and smooth, like ? A. mutans ; 

 then with four whirls sculptured as in Chrysallida, with stout 

 radiating ribs decussated with spiral strise. ? May it however 

 have belonged to a Nassa. 

 Hob. Mazatlan ; extremely rare, off Spondylus ; Upool Col. 



434. ?ALABA sp. ind. (I.) 



Tablet 1732 contains a fragment of a strong shell, with 

 smooth, prominent, strong, elongated tuberous portion, (the 

 first whirls broken) followed by divergent, somewhat rounded 

 whirls, cancellated as in Phos. 

 Hob. Mazatlan ; 1 sp. off Spondylus ; Upool Col. 



FAMILY OVULIILE. 

 GENUS OVTJLA, Srug. 



Enc. Meth. vol. xv. no. 37. Phil. Hand. Conch, p. 162. 

 Amphiceras, (Gronov.) Gray, Proc. Zool. Soc. -1847, p. 143: 



= Amphiperas, Morch. 

 Volva (Bolten) H. fy A. Ad. Gen. vol. i. p. 272. 



-V 435. OVULA VAEIABILIS, C. IB. Ad. 



Ovula variabilis, C. B. Ad. Pan. Shells, pp? 31, 304, no. 4. 



(May, 1852.) 

 Ovula California, Sow. Proc. Zool. Soc. [teste Cuming : Pubi.] 



This shell closely resembles the Atlantic species, O. unipli- 

 catum, Sow. (S. Carolina), O. aciculare, Lam. (W. Indies) and 

 O. subrostratum, Sow. (Honduras). The striae at each end are 

 extremely fine, and are rarely traceable over the whole surface. 

 The shape is sometimes stunted and broad, sometimes acuniin- 



