188$. PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 375 



Designating the prinniary lamelloe, when present, by their letters 

 and the accessories by dots, we obtain a formula for the dentition of 

 a certain species. The following table is the list of such formulae for a 

 number of North American and European species, and contains a few 

 hitherto not generally included with the Yertigos* 



Name. 



Y. pentodon, Say 



do 



do 



do 



, do 



Y.floridana, Dull. 1 2 .. 

 V. curridens, Gld. ] 3 .. 



do 



do 



V. antivertigo, Drap. 4 5 



do 



Y. ovata. Say 4 6 



do 



do 



T. ovata, var. ' 



Y. ovata, var. '. 8 



V. moulinsiana, Drp . . 



do 



Y. substriata, Jeffr. 9 . . . 



Y. pusilla, Miill. ' . 



Y. indescr "> 



Y. indegcr lI 



V. pygmcea, Drap 



do 



do 



Y. gouldii, Binu. 9 



do 



Y. califomica, Rowell ' 

 Y. Ulljeborgii, West . . . 

 Y. (n'ifcHlata.Wolf 12 .. 

 Y, ronnebyensis. West 



Y. alpestris, Alder 



Y. alpestris, Var 



Y. heldii, Cless 



P. venetzii, Charp 

 P. milium, Gld. l . . 



Origin. 



Formula. 



N. America 



do 



do 



do 



1ST. America — Tex . 

 N. America — Fla . . 

 do 



do 



do 



Europe 



do 



N. America 



do 



N. America — Ohio 



N. America, Roan Mountain 



N. America— 111 



Europe 



.... do 



do 



do 



N. America — Colo 



N. America — Mass., Ohio . . 



Europe 



, do 



do 



N. America — Mass., Conn . . 



K. America — Me., Ohio 



N. America — Pacific 



Europe, north 



X. America 



Europe, north 



... do 



do 



A B C . D E . 



A.BC.D.E 



. A . B C . . It E . 



A B C . D E 



A . B C. E . . 



.A.BC.D.E. 



A. BCDE. 



A. BC .D.E. 



ABCDE 

 .A. BCDE. 

 . A . B <_' . . D.E. 



.A. BCDE. 



.A.BC.D.E. 



..A.BC.D.E 



.ABCDE 



ABCDE 



.ABCDE 



ABCDE 



.ABCDE 



.ABCDE 



.ABCDE 



ABCDE 



ABCDE 



ABCDE. 



ABDE 



.ABCDE 



ABCDE 



ABDE 



ABDE 



ABDf" 



ABDe 



ABDe 



ABD 



BDE 



; A B C I) E + 

 A.BCD + E. 



Remarks. 



Etc. 



Etc. 

 Rare. 

 Up to: 



Sinistral. 



Sinistral. 



1 For the systematic position of these species see text below. 



2 From descriptions and figure in Proc. U. S. Nat. Mus. vm (1885), p. 261. 



3 Quite distinct from V. pentodon, to judge from specimens from many localities in several States, 

 though certain examples of either species seem- to come very near to each other. They need further 

 investigation. 



*Y. antivertigo Drap. and Y. ovata Say have, almost exactly the same dentition as to number, size, 

 and shape, and places of the single lamella?. And also as to other features of the shells, they are very 

 similar. T". ovata, in general is a little larger, of lighter coloration, the margin is somewhat more ex- 

 panded : the aperture appears larger because the columellar margin is relatively a trifle shorter; the 

 whorls increase in size somewhat more rapidly, and the suture is a trifle deeper : specimens from 

 Massachusetts are not only of the same or even a darker shade, but also of the same aud sometimes of 

 a smaller size, and other distinguishing features are slightly marked. They resemble each other so 

 much that it is difficult to separate them, and if collected at the same place no one would regard them 

 as even distinct varieties. I hesitate, however, to declare them identical because I have not vet made 

 a comparison of the soft parts. Doubtless they are parallel forms, and if found on the same conti- 

 nent, would be regarded as varieties of one species. Compare also the following notes : 



5 Y. antivertigo Drap., is remarkably constant throughout Europe so far as I know it. while 



6 Y. ovata Say is on the contrary quite variable, owing, possibly, to the greater differences in cli- 

 mate Also a few decided varieties exist and may be more will be found ; the future study of these 

 forms is likely to be of great interest. 



7 A trifle smaller than the average, perforated, the only form I know with this character. 



8 Considerably smaller, conical, shell thin, appears to be a different species, but possibly connected 

 with the types by iutermediate forms. . , „ 



9 Y. substriata Jeffr., and Y. gouldii, Binuev (fig. 3) are nearly related. In the former the lamellae 

 are usually a little larger, especially the accessory No. 1, aud the whorls larger and less in number ; 

 both are regularly striated. Accessory No. 1 (or body whorl) very small in Y. gouldii, and quite near 

 A, but absent in specimens from various localities. 



10 In general appearance similar to V. pygmcea Drap. 



" Rather large cylindrical, chestnut colored. , • /->, • j 



12 Is as valid a species as any other of North America. Collected at different places m Ohio ana 

 Illinois; verv nearly allied to Y. Ulljeborgii Westerland, of Sweden, a relation well worthy 01 Demg 

 studied more closely. In the formulas of this and the two following species the ' e infticatea tiiat 

 the upper primary lamella? in the peristome are very small or entirely wanting. Also in uujeoorgi 

 the same is quite small, to judge from the few specimens in my hands. 



