472 PROCEEDINGS OF THE NATIONAL MUSEUM. tou 53. 



ally smooth, elevated or turbinate, and often of a darker color than 

 the rest of the shell. 



De Boury has divided the genus into a multitude of sections, which 

 have a certain convenience in separating the species, but which in 

 most cases tend to merge into the adjacent groups without any very 

 marked distinction. 



The Pacific coast of America is quite rich in species and doubtless 

 there are many more tropical forms yet to be discovered. The 

 South American coast has been very imperfectly explored and very 

 few species have been reported therefrom. The older authors de- 

 scribad very briefly and imperfectly quite a number of species which 

 can only be identified by comparison with the original types, most 

 of which are in the collection of the British Museum. Perhaps the 

 best and most complete single collection is that brought together by 

 De Boury and situated in the Paris Museum. 



Owing to gross carelessness on the part of the compilers there are 

 many erroneous localities given in several of their monographs. 

 Species from the Pliilippines are ascribed to the Pacific coast of 

 America, and quite incompatible localities are given to a single 

 species. Some of these blunders will be corrected in the present 

 paper. 



The most common of our boreal species is Epitonium (Boreoscala) 

 greenlandicum Perry, 1811, with which suhulatum Couthouy, 1838 

 (not of Sowerby, 1825), and planicosta Kiener, 1838 (not planicos- 

 iata Bivona, 1842), are synonymous. The subgenus Boreoscala was 

 instituted by Kobelt in 1902; Arctoscala Dall, 1909, and Liroscala 

 De Boury, 1909, are synonymous. Its distribution is circumboreal, 

 though somewhat patchy, as it is often apparently absent where it 

 would be expected. On the Pacific coast it is found from Point 

 Barrow to Wrangell, Alaska, and the coast of Eastern Siberia; it is 

 fossil in the Pleistocene terraces of Japan. It exliibits much more 

 variability than the more southern species, both in slenderness and 

 in the number of axial ribs, which vary from 8 to 17 in number, 

 and also in the strength of these ribs. The strong spiral sculpture 

 seems to be tolerably constant. E. hempliilli Dall, 1878, from the 

 Pliocene of San Diego, is an analogous species. 



The subgenus Opalia H. and A. Adams, 1853 {Psychrosoma Tap- 

 parone Canefri, 1876), is represented on the coast by several recent 

 species and some fine Pliocene forms. The most common recent 

 species is 0. wrohlewskii Morch, 1876. This is Scalaria horealis Gould, 

 1852, not of Beck, 1839. A very solid white shell with seven or 

 eight varices, more conspicuous on the early part of the spire, and a 

 well-marked basal disk. It ranges from Forrester Island, Alaska, 

 south to San Diego, California, where it is found in 53 fathoms, and 

 also in the Pleistocene of the vicinity. 



