THE NAUTILUS. U0 
Compared with P. rhyssa, P. altissima is not only much smaller, 
but also much flatter, with the aperture consequently narrower and 
the last whorl! less evenly rounded. I have specimens of P. rhyssa 
from the original locality, collected by Mr. Ashmun ; the species 
was also found by Prof. Townsend in the White Mountains, at an 
altitude of about 8,000 feet. 
The following form, also from the White Mountains, seems worth 
defining : 
Polygyra rhyssa var. hyporhyssa v. nov. 
Like P. rhyssa in size and form, but umbilicus wider, exposing 
the penultimate whorl] ; sculpture finer, consisting of strive rather than 
riblets. Collected by Prof. C. H. T. Townsend on the lower slopes 
of Sierra Blanca, N. M., above head of Ruidoso Creek, in aspen 
belt, about 9,500 ft. alt., Aug. 14, 1898. One specimen, diam.,. 
max. 15, min. 123, alt.9 mm. This is clearly a variety of rhyssa, 
and is not the same as Dall’s MS. P. miorhyssa, which appears to 
me to be a perfectly distinct species. 3 
NEW PISIDIA. 
BY DR. V. SEEREKI. 
P. roperi n. sp. 
Mussel rather large, strongly inflated when mature, very little so 
when young; oblong to ovoid in outline, margins regularly curved, 
with no projecting angles (in the adult); scutum and scutellum 
scarcely marked ; beaks moderately posterior, very broad, surface 
somewhat glossy, with irregular, not sharp, striz and some strongly 
marked lines of growth ; color of the dry shell straw to yellowish- 
horn, often with one to several fine, concentric lines of purple; shell 
rather thin, nacre whitish, muscle insertions scarcely marked, hinge 
comparatively fine and short; cardinal teeth quite small, the right 
one moderately curved, slightly thickened at the posterier end; the 
left ones very short; the inferior slightly angular, truncated or 
pointed on top, the superior sometimes almost obsolete; lateral teeth 
short, small, scarcely projecting into the interior ; ligament rather 
fine. 
Long. 5:5, alt. 4-4, diam. 3.8 (4) mill. 
Long. 4°5, alt. 3°7, diam. 3:0 mill. 
