376 AMERICAN SPECIES OF VERTIGO 



There are apparently relations to other groups ; thus to Pupilla (partly 

 by species not named in the table), and to Leucochila, many of which 

 show nearly the same dentition as the Vertigos. 



As to deducing a final conclusion from the facts presented, in the 

 matters of relationship on the one hand and geographical-geological 

 distribution on the other, I do not at this time feel competent; an at- 

 tempt to do so might result in at least a partial failure; especially be- 

 cause the soft parts require to be compared and the fossils of the various 

 groups must yet be subjected to careful consideration. 



One question more is suggested here: Whether Vertigo is to be con- 

 sidered a genus or only a subgenus of Pupa. The leading concholo- 

 gists are of different opinions about it. It seems to me that our group 

 is by intermediate forms connected with other subgenera of Pupa, 

 therefore I still prefer to include it among the latter, though I shall 

 study the question further. 



Following the above considerations, I desire to direct the attention 

 of conchologists to some species that require to be placed among the 

 Vertigos which have hitherto been regarded as belonging to other 

 groups, and a few others that require to be removed therefrom. Among 

 the former is V. pentodon Say* (Fig. 2), and related forms; V. curvi- 

 dens GUI. (probably identical with V. pellucida Pfr.), and V. Jioridana 

 Dall. These have been recently placed in Pupilla and even in Leu- 

 cochila, although Say had already written Vertigo pentodon. In shape 

 and dentition their shells entirely agree with Vertigo, and do not agree 

 with the other named groups. Also, the soft parts, as to jaw and 

 odontophore, seem to exhibit no objection to this union. The only dif- 

 ference is the coloration of the shell, but in other genera and groups of 

 Pupa albino forms occur as well as " colored." If Vertigo pentodon had 

 a brown instead of a whitish shell it probably would have been placed 

 elsewhere. These forms certainly represent a peculiar group of Vertigo, 

 but, as before stated, their proper place is here. 



Very probably P. decora Gld., P. californica Powell, with P. rowellii 

 Newc, and a few others of our continent are to be, and for certain good 

 reasons have been, placed with Vertigo. Their general form, and more 

 specially their dentition, are sufficient reasons for so doing. When 

 Morse placed his P. corpulenta and P. bollesiana in Isthmia, it was 

 equivalent to arranging them with the Vertigos, the connection and 

 extent of Isthmia having been so restricted by European conchologists. 



P. rupicola Say, and P.corticaria Say, at one time also included with 

 Vertigo, are of a different type. Although bearing some features of 

 that group, the former is quite variable, at least in many instances. It 

 will suffice here to indicate these points; in order to settle them, more 

 study and comparison is required. 



* In r. pentodon the principal D begins also a trifle deeper in the throat than E, at 

 least in thf specimens I Lave seen from different parts of the United States. (Confr. 

 Dall /. c, p. 262.) 



