10. o 



mature individuals, and no one would think of connecting the 

 quite young of the two. 



Sjyecies. — There are very many groups in the other genera 

 of StrepomatidjB in which the species resemble one another 

 quite as closely as in lo; we may instance the close resem- 

 blance of Angitrema armigera and Duttoniana ; of verrucosa 

 and lima; of genicidata, salebrosa and suhglobosa ; of Ancidosa 

 prcerosa and tcnniata; of the species of Schizostoma ; of the 

 heavy cylindrical Goniobases of North Alabama ; and many 

 like instances will occur to those who have studied the family. 

 — Am. Jour. Conch., i, p. 41, 1865. 



In a figure included in the introductory portion of this work 

 will be found the lingual dentition of a species of this genus, 

 Jo spinosa, Lea (fig. 22). 



SYNOPSIS OF SPECIES. 



A. Shell smooth or somewhat tuberculated. 



1. lO FLUVIALIS, Sa3'. 



lo tenehrosa, Lea. 

 lo verrucosa, Reeve. 



2. lo ixERMis, Anthony. 



lo lurida, Anthony. 



B. Shell spinose. 



3. lo spixosA, Lea- 



Var. lo crassa, Anthony. 



(Monstrosity) lo gibbosa, Anthony. 

 Var. lo recta, Anthony. 

 Var. lo rhombica, Anthony. 



4. lo BEEVis, Anthony. 



lo spirostoma, Anthony. 



5. lo TUKRiTA, Anthony. 



