32 (Jumrsily of Michigav 



Height Maj Ulam. 



P. /. Hiayor; A N. S. P. 12990 21.3 116 (26.3) Tjpc ; Caracas, Ven. (Fig. v-H). 



P. t. saiitaguitcnsis (Fig. v-J ) 12.3 136 ( 16.7) H, 1, b, 42 ; smallest male. 



(Fig. v-I) 17.8 128 i22.j) Type ; largest female. 



A. N. S. P. 12993 19.2 126 (24.2) Cucuta, Colombia (Bouquet). 



The following artificial key to the mainland forms of this 

 typical group may assist in their separation, although a com- 

 parison of authentic specimens, or at least a study of the orig- 

 inal figures and descriptions, is the only practicable means for 

 their identification. The localities given are those of the orig- 

 inal descriptions, except in a few cases where the original 

 locality was omitted or was later shown to be absolutely incor- 

 rect. The figures give the altitude in millimeters, the major 

 diameter index in percentages (followed by the actual dimen- 

 sion in millimeters), and the number of whorls. As the earlier 

 writer determined the altitude in a diflferent manner from that 

 at present customary, many of these measurements are not 

 those of the author, but are those of his figure. In a very 

 few cases, the measurements are necessarily taken from later 

 authors, but such cases were checked up with original data. 

 The names given are those of the original authorities, and I 

 do not vouch for the specific separation of many of them. As 

 will l)e detailed later, the individual variation is often very 

 great, even in shells from a single locality. 



A. Costa around umbilicus; opercukun unknown. Eastern Peru. 

 14; 150(21); 6 Af>i-roitoiiia hartlciti H. Adams (i860)-. 



AA. Sides of umbilicus evenly rounded. 



B. Peristome emarginate above and below ; shell large. Costa 

 Rica. 31; 124(38.5); 5.. .C3'r/o/«.v bisinuatus Martens (1864). 



BB. Peristome not emarginate above ; shell smaller. 



C. Shell with comparatively weak, quite regular, growth lines ; 

 color light greenish to yellowish, translucid. 



