Hab. San Pedro, five alive on the sand shoal; and Half Moon Bay, beach; also San Diego. Dr. Cooper. Also fossil in the Post Pliocene, San Pedro.
No. 602, Mollusca, Survey Cabinet.
The brown lines are variable in number, the under side of one specimen showing two and of another six of these lines. The granulation of the ribs is arranged in the lines of growth.
N. Gen. PTYCHOSTYLIS, G.
Testa Calliostomati similis, conoidea; spira elevata; apertura subquadrata; columella antice truncata, plicis obliquis duabus induta, labro acuto, umbilico nullo.
Shell resembling Calliostoma, Swains, (Zizyphinus, Gray,) conical not umbilicate, internally pearly, spire moderately elevated; aperture subquadrate; columella bearing two oblique folds, the lower of which ends abruptly at the end of the columella; outer lip and base acute, smooth or internally striate; operculum unknown.
P. caffea, G.
T. conoidea, tenui; spira elevata; anfr. I nucleari, lævi, anfr. V ad marginem subangulatis, supra recte declivis, ultimo infra sub-planato; sutura valde impressa; tota superficie concentrice tuberculato costata; costis circitur XVIII ad ult. anfr.; epidermide flavida; apertura oblique sub-quadrata, intus albida.
Long. ·55, lat. ·58, long. aper. ·26, lat. aper. ·28, ang. diverg. 58°.
Shell conical, thin; spire elevated; one nuclear whorl, smooth, five perfect whorls, subangulated at the margin, obliquely flat above; body whorl very slightly convex at the base; suture strongly impressed; surface marked by revolving tubercular ribs, about eighteen on the body whorl, one broad one on the margin and about eight or nine on the under side; these ribs are less numerous on the preceding volutions, only four can be counted on the upper side of the penultimate whorl; the tubercles are arranged so as to present an irregular quincunx; epidermis a rich coffee brown, darker between the tubercules than on their summits; aperture obliquely quadrangular, outer lip and base acute, internally pearly white, columella bearing two strong folds, the lower one of which borders the truncated end and terminates in a faint tubercular enlargement; behind the columella is a slight groove running from the base to the end of the upper columellar fold.