HOLOSPIRA. 81 



Strebel and Pfeffer examined a somewhat defective speci- 

 men without exact locality, from the Berlin Museum. The- 

 sculpture consists of sharply developed, pretty close, fine rib- 

 lets, but little curved, which on the last whorl are more sepa- 

 rated and coarser. The internal axis is similar to the preced- 

 ing species, but the palatal lamella (upon the inside of the 

 outer wall) is wanting, that upon the basal wall is reduced to* 

 a callus, and the parietal one is normal. The specimen meas- 

 ures, length about 16.5, diam. 5.7, whorls 12. Possibly the 

 condition of the internal lamellae may be due to immaturity. 



Tryon's description of this species, alluded to above, was 

 contracted, with liberties, from that of Pfeiffcr, and his figure 

 is a bad copy of one in the Conchylien Cabinet. The speci- 

 mens before him from Sonora, which he gives as the locality, 

 belong to another species, H. minima. 



Section Eudistemma Dall, 1895. 



BALL, Nautilus, ix, p. 50 (Sept., 1895) ; Proc. U. S. Nat. 

 Mus., xviii, p. 3 (1895) ; xix, p. 346 (1897). 



"Penultimate whorl with a short axial and a parietal 

 lamella only, the axis moderately large. Type H. arizonensis 

 Stearns." 



7. H. ARIZONENSIS Stearns. PI. 16, figs. 1, 2. 



Shell dextral, elongately cylindrical, fusiform, dingy white 

 to pale horn color, translucent. Number of whorls 12-13, 

 slightly convex, the sutures distinctly defined. The upper 6 

 or 7 whorls rather abruptly tapering towards the obtuse apex, 

 which has a slightly twisted and rather a papillose aspect. 

 The last whorl is curved under and constricted back of the 

 mouth, forming an umbilical notch. The apex and following 

 whorl are smooth ; the three or four succeeding whorls sharply 

 and somewhat obliquely plicated longitudinally, the median 

 and following whorls becoming somewhat obscurely sculptured 

 other than by distinct growth lines. The basal whorl is 

 strongly sculptured below, and back of the mouth, and ob- 

 tusely angulated underneath. Aperture ovate, slightly angu- 

 lated anteriorly, somewhat effuse, rimmed and projecting. 



Length 12.5, diam. 4 mm. ; length 13, diam. 4 mm. (Stearns) . 



