AMERICAN SPECIES OF VERTIGO. 



121 



been published, it seems undesirable to revive that name. The 

 type of V. concinnula, from near Brush Creek, Ouster Co., 

 10,000 ft., is drawn in fig. 9. The two varieties, haydeni and 

 accedens, have never been defined. 



There are some forms approaching corpulenta, but con- 

 cinnula is more distinctly striate and has longer palatal folds. 



The specimens from Arizona and New Mexico are of a 

 clearer, more translucent cinnamon color than those seen from 

 Colorado; the crest is generally somewhat better developed. 

 Length 2 to 2.3 mm. These southern examples form a transi- 



FIG. 1. VERTIGO CONCINNULA CKLL. 



tion to V. modesta insculpta, the only difference being the 

 smaller size and generally longer palatal folds of concinnula. 

 According to Mr. Wheeler, the record from Alabama was 

 based upon an identification by the writer; but the place is 

 so remote from the known range of concinnula, and the en- 

 vironment so diverse, that possibly the identification might be 

 revised if the specimen was at hand. 



24. VERTIGO ARTHURI (Martens). 



"Shell ovate, striatulate, perforate, of 5 rather swollen 

 whorls ; the aperture triangular, outer margin thickened with- 

 in ; 2 palatal folds, 2 columellars, the upper one larger, and 

 1 strong parietal. Length 1.5, diam. 0.8, apert. 0.5 mm." 

 (Marts.) 



Vertigo bollesiana Morse var. arthuri von MARTENS, SB. 

 Ges. Nat. Freunde, Berlin, nr. 9, Nov., 1882, p. 140. 



"Little Missouri, Dakota, coll. by Arthur Krause. It dif- 

 fers from the type form of the species [V. bollesiana] by the 



