MAZATLAN UNIVALVES 245 



Hob. Mazatlan ; extremely rare, off Spondylus and Chama ; 

 L'pool Col. 



Tablet 1157 contains the perfect specimen, and the youngest, 

 with the rugae conspicuous. The other two specimens found 

 were intermediate between these extremes. 



307. PVlTBINELLA ANNULATA, n. S. 



?V. t. subglobosd, solidiore, opacd, albd, anfractibus iv. et 

 triente ; spird haud depressd, Icevi ; carind spirali ad pwi- 

 pheriam conspicud, rotundatd ; carinis duabus minoribus, aciitis, 

 quarum altera umbilicum satis magnum definat, altera inter- 

 media est ; aperturd subrotundatd, a carinis subangulatd, anfr. 

 penult, parum attingente ; suturd subimpressd ; striis nonnullis 

 spiralibus in spiram monstrantibus. 



This shell is somewhat solid and globose for the genus ; and 

 the nuclear portion not being clearly defined in the solitary 

 specimen found, its position is doubtful. It is easily recog- 

 nized by the rounded, annular keel on the periphery, with 

 two somewhat sharp ones on the base, the latter bounding the 

 umbilical region. Long. *027, lat. "052 by '047, div. 150. 

 Sab. Mazatlan ; 1 sp. off Chama ; L'pool Col. 



Tablet 1158 contains the specimen. 



308. VlTEINELLA CINCTA, n. S. 



V.\t. subglobosd, albd, anfractibus iv. tumidis ; carinis duabus 

 majoribus, acutis, haud valde prominentibus, haud distantibus, 

 utroque latere peripheries planatce spiraliter cingentibus ; duabus 

 quoque in basi minoribus ab umbilico prqfundo, haud expanso, 

 et peripherid cequidistantibus ; spird subplanald ; striis passim 

 spiralibus ; aperturd a carinis angulatd, anfr. penult, parum 

 attingente; regione inter umbilicum ipsum et carinam profunde 

 concavd ; anfractu ultimo parum declivi. 



The two principal keels are much closer and less prominent 

 than in V. bifrontia. In the base it resembles Y. annulata, 

 but the spiral portion is quite different, being flattened, with 

 very numerous spiral striae, The whirls do not enlarge rapidly. 

 The umbilicus itself is somewhat narrow, with a broad funnel 

 leading down to it from the nearest keel. The labium is some- 

 what reflexed over it. Long. '02, lat. '034 by "028, div. 170. 

 Hob. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



Tablet 1159 contains the specimen. 



