HOLOSPIRA MESOLIA, n. sp.
The shell is cylindric-fusiform, of a delicate pink-white tint, the
upper part white with blue stains; dead shells white throughout.
Whorls 14, the first 2½ smooth, forming the mamillar embryonic shell, the first whorl rapidly increasing, second swollen, next half
whorl very narrow. Subsequent whorls are nearly fiat, rather finely
but strongly striate, regularly increasing to the 8th or 9th whorl,
where the shell reaches its greatest diameter. After that the whorls
are nearly smooth, rather glossy, and the shell diminishes slowly in
diameter to the base. The last two whorls have retractive axial
ribs which gradually increase in strength, and are strongest on the
straight part of the last whorl and base. The last whorl is somewhat, compressed laterally and projects, carrying the aperture well
forward. Aperture is very shortly ovate, almost circular, light brown
within. Peristome very broad, flatly reflexed, white. The internal
axis is smooth throughout, rather slender, tapering downwards, with
a diameter of about 1 mm. in the widest part.
Length 23.5, greatest diam. 6 mm.; whorls 14.
Length 22.6, greatest diam. 6.3 mm.; whorls 13½.
Length 20, greatest diam. 5.8 mm.; whorls 12¾.
Sanderson, Terrell Co., Texas, on a low limestone ledge along the
railroad. Elevation 2800-2900 ft. Types no. 107001 A. N. S. P.,
collected August 25, 1912 by Messrs. Morgan Hebard and J. A. G. Rehn.
This handsome Holospira is most closely related to H. semisculpta
Stearns, which was described from a canyon above San Carlos,
Chihuahua, a place on the Mexican side of the Great Bend of the
Rio Grande. Dr. Dall and Dr. Bartsch have kindly compared
specimens with the type of semisculpta, and report that the new
species "differs in the profile, which in your shell is more contracted
toward the base, rendering it spindle-shaped, while the former is
more cylindrical. The ribs in yours do not extend over so many of
the basal whorls, and the expanded peristome gives it a very distinct
appearance. It is doubtless a distinct species."
With the Holospira were found specimens of Polygyra texasiana texasensis and a Succinea.
