GASTROCOPTA. 201 



( A callus below the eolumellar lamella. 

 \± \ G. procera, xxiv, 62. 



I No callus below eolumellar lamella. 

 ^ G. p. riparia, xxiv, 65. 



r A strong crest behind the lip ; 2.3 to 3.2 mm. long, more 

 than 1 mm. wide. Oklahoma to Arizona. 

 15. \ G. cristata, xxiv, 68. 



I Length 2 to 2.2 mm., diam. 0.9 mm. Bimini Islands. 

 ^ G. p. biminiensis, xxiv, 78. 



' Having 5 or more well-developed teeth ; a basal fold 

 present (17). 

 Having 4 strong teeth, the anguloparietal almost simple ; 



16. <j no basal fold; shell whitish; New Mexico and Ari- 



zona. G. quadridens, xxiv, 57. 



Teeth small (3 to 5), a basal fold usually wanting; upper 

 [ palatal fold minute when present (22). 



r Diam. above aperture usually more than 1 mm., about 



17. < 2.5 mm. long; brownish (18). 



vDiam. 1 mm. or less; length 1.5 to 2.6 mm. (19). 



' No crest behind the lip ; angulo-parietal lamella not 

 strongly bifid ; no infraparietal tubercle. 



G. servilis, xxiv, 70. 

 A narrow crest; angulo-parietal lamella bifid; an infra- 

 parietal tubercle often present. 



G. riograndensis, xxiv, 69. 



( Angulo-parietal lamella strongly bifid ; a callus or tooth 

 -iq I below the eolumellar lamella (20). 



| Angulo-parietal sinuous or emarginate but not distinctly 

 ^ bifid. G. pellucida and varieties, xxiv, 75. 



r Lower-palatal fold very long, its inner end not visible 

 20. -j in a front view. G. curacoana, p. 197. 



v. Lower-palatal fold not very long (21). 



oi f An infraparietal tubercle present. G. polyptyx, xxiv, 89. 

 I No infraparietal tooth. G. barbadensis, xxiv, 83. 



18 



