AET. 10 NEW VICKSBUEG MOLLUSKS FROM MEXICO COOKE 5 



GEMMULA MEXA var. MEXITA, new variety 



Plate 1, Figure 4 



Variety mexita differs from typical G. Tnexa in having three threads 

 on the anal f asciole and several faint threads on the posterior slope. 

 Occurrence. — With the preceding. (M. 49 V.) 

 Type.—Q2it. No. 352694 U.S.N.M. 



PSEUDOTOMA ALAZANA, new species 



Plate 1, Figure 5 



Shell obese, apical angle about 62° ; nucleus smooth, of two and 

 one-half convex whorls ; subsequent whorls medially carinated, loosely 

 appressed, ornamented with close low corrugations marking growth 

 stages and many fine revolving threads; posterior slope concave; 

 anterior slope nearly straight to the suture; base of body whorl 

 concave to the sutural band ; anal sinus shallow, situated between the 

 suture and the carina. Length of nucleus and three and one-half 

 postnuclear whorls, measured to the carina, 9 mm. ; breadth, 9 mm. 



Occwrrence. — Oligocene, Alazan clay, Rio Buena Vista, west of 

 Alazan, Mexico. (M. 49 V.) 



Type.—C^t. No. 352697, U.S.N.M. 



SCOBINELLA PRIONOTA, new species 



Plate 1, Figures 6, 6a 



Shell polished, slender, apical angle about 35°, whorls appressed, 

 peripheral outline serrate ; tip of nucleus obtuse, with about three and 

 one-half convex whorls, smooth except last one-fourth whorl, which 

 is axially ribbed; subsequent whorls, T in type, coronated; posterior 

 half of whorl concave to a strong antesutural thread ; middle of con- 

 . cavity occupied by a nodular thread which marks the deepest re- 

 entrant of the anal sinus ; coronal band divided by a groove which on 

 the earlier whorls is medial but on the later whorls is anterior to the 

 nodes on the corona; nodes of corona blunt, serrate, twelve on the 

 seventh whorl ; suture bordered by nodular threads, the anterior being 

 stronger than the posterior; base of body whorl cancellated, axial 

 outline serrate ; aperture rather narrow, less than half the length of 

 the shell; canal straight; outer lip broken, inner lip with two prin- 

 cipal columellar folds and three or four faint secondary folds. 

 Length (anterior tip broken), 15.5 mm.; breadth, 6 mm. 



Occurrence. — Oligocene, Alazan clay, Rio Buena Vista, west of 

 Alazan, Mexico. (M. 48 V.) 



Type.—Cfit. No. 352696, U.S.N.M. 



