ART. 10 NEW VICKSBUEG MOLLUSKS FROM MEXICO COOKE 7 



narrow; canal short; basal notch shallow; basal fasciole narrow,, 

 marked by two grooves. Length, 7 mm. ; breadth, 2.8 mm. 



Some specimens of this species preserve traces of the original color. 

 The shell appears to have been light brown with a darker line at 

 the suture and a nearly white band of enamel behind the suture. 



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

 Alazan, Mexico. Abundant. (M. 48 and M. 49 V.) 



Type.— Cat. No. 352700, U.S.N.M. 



PROTONEMA, new genus 



Melanellids having the nuclear whorls spirally threaded. 

 Genotype. — ProtoneiTna hartschi., new species. 



PROTONEMA BARTSCHI, new species 



Plate 1, Figures 10, 10a 



Shell robust, apical angle about 28°; suture impressed; nuclews of 

 about four whorls, dextral, first whorl very minute, others con vet, 

 with three spiral threads ; later whorls polished and smooth except f o r 

 faint axial growth lines ; first and second postnuclear whorls globular, 

 later whorls flattened; fifth and subsequent whorls constricted in 

 front of the suture, giving rise to an antesutural collar ; parietal wall 

 free from callus; outer lip broken in all the specimens at hand. 

 Length, 5 mm.; diameter, 2 mm. Another specimen attained a 

 length of 7 mm. and a diameter of 3 mm. 



Occurrence. — Oligocene, Alazan clay, Rio Buena Vista at La Ceiba 

 Alazan, Mexico. (M. 49 V.) 



Type.—Cdit. No. 352701, U.S.N.M. 



TURRITELLA CEIBANA, new species 

 Plnte 1, Figures 11, 12 



Shell long, slender, apical angle 12° to 14° ; suture deeply im- 

 pressed; whorls decorated with tw^o pairs of raised beaded threads 

 adjacent to the suture and one lower beaded thread in the depressed 

 medial region. Length of a broken specimen of nine whorls, 33.5 mm. ; 

 diameter at larger end, 8.75 mm. ; diameter at smaller end, 3 mm. 



This species somewhat resembles T. praecellens Brown and Pilsbry, 

 but lacks the fine riblets and differs in other details of sculpture. 



Occurrence. — Oligocene, Alazan clay, Rio Buena Vista at La Ceiba 

 road crossing, Vera Cruz, Mexico (M. 53 V.) ; Antigua, B. W. I.^ 

 Cat. No. 167006 U. S. National Museum. 



Type.— Cat No. 352702, U.S.N.M. 



