Page:Land Mollusca of North America (north of Mexico) Vol. II Part 2 (2nd half).pdf/103

LAND MOLLUSCA 893 Subgenus STAUROTREMA new subgenus

The shell is translucent white, cylindric, without prelabral crest; aperture with four teeth in form of a cross: a strong, nearly simple angulo-parietal, smaller columellar lamella and upper and lower palatal folds. Type G. quadrudens.

Gastrocopta quadridens Pilsbry Fig. 480: 7, 10.

Bifidaria qitadridcntala Sterki, 1899, Nautilus, 12:125. Not 1'npu quadridcntata

Klein, 1853, also a Gastrocoptu.

Bifidaria quadridens Sterki, Pilsbry & Vanatta, 1900, Proc. Acad. Xat. Sci. Pliila.,

p. 607, undefined (lapsus calami).

Gastrocopta quadridens Pilsbry, 1916. Man. Conch.. 24:57, ]>1. 10. fins. 7. 10.

The shell is subcylindric, slowly tapering upward, the apex obtuse; trans-

lucent whitish; of 6 convex whorls, the last with a slight impression over the

lower-palatal fold but no crest behind the lip. Peristome thin, moderately

expanded, with four teeth in form of a cross: angulo-parictal lamella strong,

nearly simple; columellar lamella and lower-palatal fold smaller but well

developed; upper-palatal fold smaller than the lower.

Length 2.7 mm., diameter 1.3 mm.

Length 3.1 mm., diameter 1.3 mm.

New Mexico: Capitan Mts., Lincoln Co., Type 62.21981 Carnegie Mus. (K. H. Ash-

nitin); Mogollon Mts., Socorro Co.: Black Range. Siena and Grant counties (Ferriss

and Pilsbry). Arizona: Bill Williams Mt.. Coconino Co. (Pilsbry and Ferriss); Mt.

Mingus, near Jerome, Yavapai Co. (Ashmun); Santa Calalina and Chiricahua Mts.

(Ferriss). Utah: Fish Lake, Sevier Co. (Chamberlin).

This is a strikingly distinct species. By the very thin, translucent,

paraffin-white shell, without a crest behind the thin lip, it recalls G. corti-

caria, which is perhaps the species most nearly related. The angulo-parietal

lamella is simple, as in pentodon or pihbryana, or sometimes an extremely

minute trace of the forward end of the parietal lamella, appearing as a

branch on the columellar side, may be seen near the outer end. The lower

or free edge of the parietal lamella is bent towards the columella as in G.

cristata. The lower-palatal fold is usually rather long. The columellar

lamella is transverse, as in the procera group, and there is no callus below

it. In a great number seen, none has a basal fold.

It is a common shell in the heavily forested and humid upper zone of the

Generated on 2012-12-12 12:52 GMT / http://hdl.handle.net/2027/uc1.31822000620260 Public Domain, Google-digitized / http://www.hathitrust.org/access_use#pd-google

Santa Catalina Mountains, north of Tucson, Arizona, and in the Black

Range, New Mexico, but very rare in the Chiricahua Range, at tlie southern

limit of the species, where it occurred in Barfoot Park, 10,000 ft. elevation.

Its stations are chiefly between 7,000 and 11,000 ft.

Subgenus PRIVATULA Sterki

Privatula Sterki, 1S93, Nautilus, 6: 101, monotype P. curticaria Say.

The shell is whitish, without palatal callus or folds, the columellar

lamella minute, tubercular; angulo-parietal lamella small and straight, its

crest bilobed.