MOLLUSCA OF MICHIGAX— WALKER. 48^ 



Dentition as usual in the family. 



Fig. 67. Dentition of G. intertexta. (Binney.) 

 KEY TO THE SPECIES OF GASTRODOXTA. 



I. Aperture wTth internal teeth on base of shell suppressa. 



II. Aperture edentulous, callus deposit on base of shell. 

 a. Spire somewhat elevated, acute. 



h. Surface distinctly obhc|uely striate, not shining intertexta. 



bb. Surface shining, very finely striate ligera. 



aa. Spire depressed, obtuse, surface shining demissa. 



QASTRODONTA INTERTEXTA (Binney). 



Shell perforated, subp}Tamidal; yellowish horn-color: 

 whorls 6-7, slightly angled, closely and finely striate; strife 

 .^ .^ ^ cut by very minute spiral lines; usually \\ith a narrow, light- 

 ' ^~' colored band and an ill-defined broT^Tiish band below it, fre- 

 quenth', however, unicolored; aperture rounded, a little 

 transverse; peristome thin, thickened ^Tthin by a callus de- 

 Fi^ 68 posit, umbilical perforation small; base whiter than the up- 



G. intertexta. ( Binney. )'peT SUrfaCC. 



Alt. 10, greater diam. 15, lesser 13^ mm. 

 Helix intertexta. Binnev, Bost. Jour. Xat. Xist.. III.. 413, pi. XX.. fig. 2. 



(1840). 

 Zonites infertextus. W. G. Binnev. Man. Am. Land Shells. 214, fis. 226. 

 (1885). 

 Rare in Michigan. Sanilac county is the only kno'^m locahty. Distin- 

 guished from G. ligera by its greater size, coarse, unpolished, striate surface 

 and angulated body whorl. 



QASTRODONTA DEMISSA (Binney). 



%ij_^ Shell perforated, depressed-convex; yello\\ish horn-color, shining: 

 ^P"^ whorls 6, minutely striate; spire obtusely convex; suture impressed: 

 C.j!B^apenure transverse, not large, slightly obhque, a white callus deposit 

 ^lli^on the base; peristome thin, acute; base rather flat, smooth; umbilical 

 /SmSa I'^&io^ somewhat impressed. 

 (Bmney./ Alt. 6, greater diam. 11^, lesser 10^ nam. 

 Helix demissa, Binnev. Bost. Jour. Xat. Hist., IV.. 361. pi. XVI. fis;. 16. 



(1843). 

 Zonites demissus, W.G. Binney, Man. Am. Land Shells, 212, fig. 223, (1885) . 



Very rare. Kent county is the only locahty reported. Very similar to 

 G. ligera in color and texture, but differs in size" and shape, being more de- 

 pressed and the spire being convex ^Tth an obtuse apex. G. ligera is larger, 

 more strongly striate, the body- whorl is more ventricose and the spire more 

 elevated and acute. 



