OF NORTH AMERICA. 447 



A comparison of the types of apicina with a large set of shells 

 from Lake Superior shows that both are the same species. The Lake 

 Superior forms are larger than the types but are otherwise the same. 

 Lea's figure is wretched and gives no idea of the shape of the shell and 

 his description is totally inadequate to recognize the species. Binney's 

 figure 86 (catascopium?) represents apicina, the four figures showing 

 something of the range of variation. Haldeman's fig. 5, on plate 14 

 is a good representation of apicina but is not related to decollata, as 

 thought by Haldeman. Haldeman's fig. 12, on plate 11, is also this 

 variety. The types of apicina (two specimens) are smaller than the 

 Lake Superior and Michigan forms referred to this variety, but they 

 are otherwise the same. (See plate XLVIII, fig. 1). Specimens from 

 Oregon are identical and of the same size as the Michigan specimens. 

 Conchologists have generally misunderstood this species, placing it as 

 a synonym of solida and confounding it with decollata. The Michi- 

 gan and other western references to decollata refer either to solida 

 or apicina. The specimens examined from this region have nearly all 

 proved to be apicina and not a single undoubted specimen of decollata 

 has been detected among them. Apicina differs from the variety solida 

 in being more regularly ovate or bulbous, having more tumid whorls, 

 a slightly open umbilicus, a sharper and more conspicuous columellar 

 plait and generally a more depressed and dome-shaped spire. 



It is evident from a study of the types of binneyi Tryon that 

 apicina is very closely related to that species. The chief differences 

 are the more tumid shell with its short, depressed spire in apicina, 

 which is long and more acute in binneyi; the closed or nearly closed 

 umbilical chink in apicina is in strong contrast with the wide, flat in- 

 ner lip and open umbilicus of binneyi. Individuals of one species vary 

 toward the other, but on the whole these distinctions hold good. Some 

 conchologists might consider these varieties of the same species, but 

 while undoubtedly closely related, they are, apparently, specifically 

 distinct. Young specimens of emarginata mighelsi somewhat resemble 

 apicina, but the shape of the whorls, their less number and the large 

 umbilicus, will distinguish them. The Michigan specimens vary greatly 

 in size and form. Individuals from the Menominee River are small 

 with a somewhat elevated spire and rather narrow shell, which is 

 much eroded by the carbon dioxide in the water. Specimens from 

 Iron County are larger and more tumid, with depressed, rotund spire 

 and a well-marked columella plait. The forms from Union River 

 are the same as those from Lake Superior. 



The reference of Bell, Whiteaves, etc., to solida and apicina from 



