1922] NATURAL SCIENCES OF PHILADELPHIA 89 



Micrarionta wolcottiana (Bartsch 1903) Plate I, fig. 3. 



? 1890. Helix Traskii, form, Orcutt, Nautilus, vol. 4, p. 67 (recorded from 

 Palm Canyon and Snow Creek.) 



1903. SonareUa wolcottiana Bartsch, Proc. Biol. Soc. Wash., vol. 1G, p. 103. 



1904. Sonorella wolcottiana Bartsch, Proc. Biol. Soc. Wash., vol. 17, p. 101. 

 (emended spelling). 



1904. Sonorella wolcottiana Bartsch, Smiths, Misc. Coll., vol. 47, p. 187, 188, 

 pi. 28; pi. 31, fig. 4. 



1905. Sonorella wolcottiana Pilsbry, Proc. Ac. Nat. Sci. Phila., 1905, p. 254 

 (passing mention). 



1908. Micrarionta wolcottiana Pilsbry & Ferriss, Nautilus, vol. 21, p. 135 



(brief note). 

 1918. Micrarionta wolcottiana Pilsbry, Proc. Ac. Nat. Sci. Phila., 1918, p. 



139, text fig. 1 (anatomy). 

 1921. Micrarionta wolcottiana Pillsbry, Nautilus, vol. 35, p. 48 (noted north 



of Palm Canyon). 



The shell of this species has already been well described and fig- 

 ured by Bartsch (:03, :04a) although many more figures will be re- 

 quired to show the remarkable variations to which even the mem- 

 bers of a single colony are subject. Certain anatomical features of 

 taxonomic importance have likewise received treatment at the com- 

 petent hands of Pilsbry (:18). To the published information the 

 following color notes on the shell and animal may well be added. 



The body of the living animal is Chaetura drab passing to drab at 

 the margin, and with a narrow stripe of hair brown along the medio- 

 dorsal line. The sole is wood brown shading to avellaneous at the 

 margin. The shell on the living animal is white (on its thicker 

 portions), passing through vinaceous buff and intermediate shades 

 to hair brown. The empty shell of the adult is light in tone, the 

 body whorl varying from Tilleul buff to avellaneous, paling on the 

 spire to cartridge buff or almost to pinkish buff, and in the 

 immediate vicinity of the umbilicus to pale vinaceous fawn or 

 almost white. The shoulder band, usually bordered above and 

 below by a similar band of whitish, is quite a dark liver brown, 

 often showing a sort of breaking up into two components, the 

 d arker one appearing with odd effect to overlie a lighter and brighter 

 one of cinnamon rufous tone, Young and immature shells before 

 the formation of the peristome are invariably much darker and 

 brighter in color than the adults, the body of the shell a rather 

 light snuff brown, toning to avellaneous on the spire and vinace- 

 ous buff at the umbilicus. 



Fifteen specimens in the collection of Allyn G. Smith yield the 

 following caliper measurements: 



