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 alternate Say, pi. xxviii, figs. 19, 21, 22 23, 24. 

 Helix alternata SAY, Nicb. Encycl., pi. i, fig. 2, 1817-1819. 

 Helix scabra LAMARCK, An. sans. Vert., Vol. VI, pt. 2, p. 88. 

 Helix mordax SHULT, Bern. Mitt., p. 195, 1853. (Variety.) 

 Helix strongylodes PFEIFFER, Proc. Zool. Soc., p. 53, 1854. 

 Helix infecta PARREYSS, MS., Pfeiffer, Mai. Blatt., p. 86, 1857. 

 Helix dubia SHEPPARD, Trans. Lit. Hist. Soc. Quebec, Vol. I, p. 194. 

 Helix fergusoni BLAND, Ann. N. Y. Lye., Vol. VII, p. 421, 1862. (Va- 

 riety.) 

 Helix alternata var. costata LEWIS, Amer. Journ. Conch., Vol. VI, p. 



188,1871. (Variety.) 

 Helix 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 striae; 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. 

 " 21.00; " 19.00; " 14.00; " " 6.00 " 



21.00; " 18.00; " 12.50; " " 5.50 " 



" 20.00; " 17.00; " 12.00; " " 5.00 " 



" 20.00; " 16.50; " 10.00; " " 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 



