206 THE CHICAGO ACADEMY OF SCIENCES. 
peduncles retracted between the branches of the genitalia.” 
( Pilsbry.) 
For jaw and radula see the following species: 
79. Pyramidula alternata Say, pl. xxviii, figs. 19, 21, 22 25, 24. 
Helix alternata SAY, Nich. Encycl., pl. i, fig. 2, 1817-1819. 
Helix scabra LAMARCK, An. sans. Vert., Vol. VI, pt. 2, p. 88. 
Felix mordax SHULT, Bern. Mitt., p. 195, 1853. (Variety.) 
Helix strongylodes PFEIFFER, Proc. Zool. Soc., p. 53, 1854. 
Helix infecta PARREYSS, MS., Pfeiffer, Mal. Blatt., p. 86, 1857. 
Flelix dubia SHEPPARD, Trans. Lit. Hist. Soc. Quebec, Vol. I, p. 194. 
flelix fergusoni BLAND, Ann. N. Y. Lyc., Vol. VII, p. 421, 1862. (Va- 
riety.) 
Flelix alternata var. costata Lewis, Amer. Journ. Conch., Vol. VI, p. 
188, 1871. (Variety.) 
flelix alternata alba TRYON. 
Pyramidula alternata carinata PILSBRY, Proc. Phil. Acad., p. 490, 1896. 
(Variety). 
Pyramidula alternata rarinotata PILSBRY, The Nautilus, Vol. XIII, p. 
114, 1900. (Variety.) 
Pyramidula alternata knoxensis PILSBRY, The Nautilus, Vol. XV, p. 
6, 1901. (Variety.) | 
Shell: Depressed, rather thin, widely umbilicated; sur- 
face dull, covered with strong, oblique, rib-like striz; color yel- 
lowish horn with numerous reddish flames which extend ob- 
liquely from suture to suture, sometimes broken but generally 
entire; on the base of the shell the flames are interrupted so 
that a light yellowish or horn-colored band is formed, although 
in some specimens this is not developed; periphery slightly or 
heavily carinated; sutures very deeply impressed; apex of shell 
smooth; whorls five and one-half, gradually increasing, rather 
flat; spire elevated or depressed; aperture obliquely rounded, 
showing the color of the outer surface through the shell; peris- 
tome simple, sharp, terminations connected by a thin callus; 
columella subreflected; base rounded; umbilicus large, wide 
and deep, showing all the volutions to the apex. 
Greater diam., 22.00; lesser, 19.50; height, 15.00; umbilicus diam., 6,00 mill. 
‘ 6O El OOS ts Sit Pe a 14.00; $ 6.00 * 
3 Bn A ge Soe 13.00;55. © 12.50; ) a 5.00 “ 
i i 20.00 Se ROB ree ss TALS sf i 5.00 “ 
ry = 20,005 © eo BGS oy es 10.00; ae o 5.50 
(All measurements from set 10142, showing variation in height of spire.) 
Animal: With a long and narrow body; color of back, 
brown, of rest of upper surface brownish, with a tinge of or- 
ange, collar saffron-colored; eye-peduncles and head slaty, 
with the black eyes at the extremity of the former; tentacles 
