HOLOSPIRA. 79 



cord-like. The third lamella, running on the inside of the 

 outer wall of the penultimate whorl, is a rather low, narrow 

 and short callus, showing through distinctly from the out- 

 side. All three lamellae are glossy white (fig. 36). Strebel 

 gives the length of a specimen from Cuming as 15.7 mm., 

 whorls 16. 



Von Martens remarks that the specimen taken by IJhde "is 

 very much shorter (length 12 mm.) than that of Cuming, and 

 it has only 14 instead of 15-16 whorls ; but in the diameter of 

 the whole shell and in the size of the aperture they are alike. 

 All are probably from central Mexico. ' ' 



5. H. NELSONI Pilsbry, n. sp. PI. 22, figs. 42, 43, 44. 



Shell rimate, cylindric-tapering, the cylindric lower portion 

 passing imperceptibly into the tapering upper half; thin but 

 moderately solid ; white, more or less extensively stained with 

 blue, and with streaks and dots of blue or dark flesh- col or, the 

 intervals between the white riblets on the base and several 

 early whorls being brownish flesh-colored. Whorls 151/2, the 

 first two smooth, following 5 or 6 closely and sharply striated 

 obliquely, this sculpture then becoming more obtuse, chang- 

 ing to very low, rather coarse riblets, more or less obsolete in 

 places, and usually so in the middle of each whorl; on the last 

 whorl these riblets become narrower, stronger and closer, on 

 its latter half still closer and sharper; and they extend over 

 the convex basal. The last whorl is very shortly produced 

 forward, flattened above, angular outwardly. Aperture ver- 

 tical, obliquely rounded-piriform, contracted and angular at 

 the upper external extremity, the margins straightened on 

 each side of the angle, elsewhere arcuate; peristome white, 

 expanded and somewhat thickened. Interior brown. Inter- 

 nal pillar small, of about equal size above and below, the 

 lumen of the penultimate whorl contracted by four lamellae: 

 a strong, thick-edged axial lamella, not over one whorl long, 

 and barely entering the last whorl; a larger lamella on the 

 parietal wall, arising rather suddenly and decreasing gradu- 

 ally, nearly one whorl in length, about half of this being in the 

 antepenult, whorl; a low palatal fold about % whorl long on 



