178 Annals of the Carnegie Museum. 



striae or undulations of the shell. With these facts in mind, an exam- 

 ination of the above descriptions will decrease the list of species. 



Pleii7'otoma7'ia pauper Billings differs from Pleurotomaria crevieri 

 Billings only in that it has a flat spire and open umbilicus. The 

 specimen on which the former was founded is a cast, so its characters 

 really are what we would expect to find in a cast of Pleurotomaria 

 crevie7'i. 



Pleurotomaria crevieri differs from Pleurotomaria calyx in its smaller 

 size and its rounded instead of beveled outer margin. Both of these 

 characters are comparatively unimportant. An examination of the 

 types shows that they belong to the same species. 



Pleurotomaria calyx Billings differs from Raphistoma stamineum 

 Hall only in the lack of the umbilicus. As above stated, this is due 

 only to the removal of the lower part of the shell. Therefore, Pleu- 

 rotojnaria pauper, Pleurotomaria crevieri, Pleurotomaria calyx, and Ra- 

 phistoma stamineum Hall, all agree in their essential characters, and 

 probably represent but one species. 



Raphistoma planistrium parvum Hall differs from Raphistoma plan- 

 istrium only in size and in the distinctness of the striae, which cer- 

 tainly are not important- differences and cannot hold, even for a 

 varietal name. 



Raphistoma planistrium Hall differs from Raphistoma stami7ieu?n in 

 the greater proportional height, the narrow trigonal aperture and the 

 small umbilicus. Of these three differences, two, the height and the 

 small umbilicus, may be disregarded. The size of the aperture is not 

 indicated in the description of Raphisto77ia sta77ii7iewn nor in the figure 

 of Raphisto77ia planistriu7n, so they cannot be compared. In the 

 writer's collection there are specimens which correspond exactly to 

 the figures and description of Raphisto7/ia sta77wieu77i, Raphisto7na 

 pla7tist7'ium and Raphisto7na pla7iist7'iii7n parvu77i, and yet there can be 

 found no distinction on which to base a separation of the specimens 

 into species. It is true also that none of the descriptions apply to the 

 really perfect shells which occur with the ones which fit the above 

 names. 



Raphistoma striatum (Emmons). 

 (Plate XLVII, figures 4-10. ) 

 Maclurea striata Emmons, 1842, Final Report of the Second District 

 of the New York State Survey, p. 312, fig. 3. 



