The typical specimen of M. inflata differs from M. pupilla (with which Dr. Carpenter drew no comparisons in his description,) only in having the revolving ribs slightly less evident than in the typical pupilla. In the deep suture, inflated whorls, small internally striated umbilicus, depressed form and strong lines of increase, it is paralleled by many of the two hundred or more specimens of pupilla now before me. The ribs on the upper whorls of inflata are quite as strong as in pupilla, and the differences, though evident, are so slight and the variation in members of this genus is so great, that I am of the opinion that the two species are really extremes of one form and that the name inflata is at most entitled to no more than varietal rank. The variety sahnonea, as shown long since by Dr. Cooper, is simply the southern form of pupilla, and hardly distinguishable from it, even by differences of degree.
The small amount of material upon which Dr. Carpenter has founded so many specific names, has been so largely reenforced of late that a considerable amount of consolidation is likely to ensue. There are other cases which I might have touched upon, but I have only done so when it seemed that no reasonable doubt could exist in regard to the matter, and never without a careful study and comparison of the original type specimens in connec¬tion with the large series of my own collecting.