(Sh) 
HOLOSPIRA. 27 
HOLOSPIRA. 
Cylindrella, subgen. Holospira, v. Martens, in Albers’s Die Heliceen, ed. 2, p. 39 (1860). 
Shell ovate, fusiform, or turrite, preserving all the whorls (or nearly so) in the adult state; aperture with 
continuous, somewhat expanded peristome, more or less protracted beyond the suture of the last whorl 
(except in H. tryoni, var. appressa). Columellar axis hollow. Only longitudinal (vertical) sculpture. 
Coloration mostly uniform, pale. Size moderate. 
Confined to Central America, Mexico, and the Southern States of North America. 
Subgen. HoLospira, s. str. 
Cylindrella, subgen. Acera, Albers, Die Heliceen, ed. 1, p- 209 (1850) (nee Cuvier). 
Holospira, Crosse & Fischer, Journ. de Conch. xviii. p- 18 (1870) ; Miss. Scient. Mex., Mollusca, 
i. p. 318. 
Holospira, Metastoma, and Bostrichocentrum, Strebel, Beitr. Mex. Land- und Siissw.-Conch. iv. 
pp. 80-82 (1880). 
Shell ovate or moderately turrite, often with the largest diameter higher up than in the penultimate whorl— 
fusiform at the middle and clavate near the upper third—composed of 11-19 whorls, the upper ones 
increasing rapidly and forming a short conical upper end, as in Pupa, the middle ones increasing very 
slowly or not at all; where this difference is very marked, the shell looking like a tower with a rather 
low roof, it may be called tectiform. Aperture not very much protracted, often obliquely pear-shaped, 
having the upper margin straight and the upper outer corner pointed and projecting. This angle is 
usually continued on the protracted part of the last whorl as a light keel (dorsal keel), while the base of 
the last whorl is in most species rounded, or compressed and keeled ; the basal keel more or less disappears 
near the aperture. Columellar axis forming a rather wide hollow tube in the interior of the shell, smooth 
externally, narrowing at the base and usually opening in a narrow chink, in one species only as a round, 
comparatively large hole (umbilicus). Spiral lamella in some species well developed within the second 
or third whorl before the last, in others rudimentary or wanting. Teeth of the radula often somewhat 
pointed, more than in the subgenus Hpirobia (Fischer & Crosse, Miss. Scient. Mex., Mollusca, i. t. 16. 
fige. 7,9; Strebel, Beitr. Mex. Land- und Siissw.-Conch. iv. t. 13. fig. 1). 
Geographical range extending from Mexico into Texas, Arizona, and Lower 
California, but not reaching Guatemala in the south. These shells are found chiefly 
on the elevated central plateau, on Cactacez, and apparently occur, when found, in 
considerable numbers. But they have been met with hitherto in very few localities, 
and as several of them vary considerably in the proportion of the length to the diameter 
of the shell in the same locality, the species are rather difficult to separate in some 
instances. 
1. Holospira imbricata. (Tab. XVI. fig. 25.) 
Cylindrella (Holospira) imbricata, v. Mart. Malak. Blatt. xii. p. 15, t. 1. figg. 2, 3 (1865) *; Pfr. 
Monogr. Helic. Vivent. vi. p. 390 *. 
Holospira imbricata, Fisch. & Crosse, Miss. Scient. Mex., Mollusca, i. p. 336°, 
Hab. Mexico, without nearer indication of locality (UAde 1~*). 
This very distinct species does not appear to have been found by any subsequent 
collector; it differs from all others of the genus in the short, club-like form of the 
BIOL. CENTR.-AMER., Terr. and Fluviat. Mollusca, December 1897. 35 
