74 COOK 



Unotcenia chionophila BOLLMAN, Bull. 46, U. S. Nat. Mus., p. 123, 1893. 

 COOK, The Fur Seal and Fur-Seal Islands of the North Pacific Ocean, 

 pt. 4, 350, 1898. 



Tomotania, chionophila COOK, Am. Naturalist, xxix, p. 866, 1895. 



The Harriman Expedition secured numerous specimens of this 

 species at Popof Island, Sitka, Lowe Inlet, and at Karluk on Kadiak 

 Island. It is apparently very common in some localities. The U. S. 

 National Museum has two vials containing more than fifty specimens 

 each from St. Paul Island, Pribilof Islands, and from Unalaska, col- 

 lected by Professor Kincaid in 1897. 



Dr. Leonhard Stejneger secured this species on Bering Island, and 

 Mr. Barrett-Hamilton on Copper Island. 



Among the numerous specimens of Escaryus sibiricus in the Ham- 

 burg Museum are a few individuals of this or a closely allied species 

 collected at Vladivostock, Siberia, by Graeser. A female in this lot 

 has 43 pairs of legs. 



Family GEOPHILID-ffi. 



ANALYTICAL KEY TO THE WEST AMERICAN GENERA OF GEOPHILID^B. 



Cephalic lamina much longer than broad ; prehensorial sternum with- 

 out lateral sulci ; sterna with three longitudinal impressed lines. 



Genus Mecistocephalus. 



Cephalic lamina but little broader than long; prehensorial sternum 

 with lateral sulci ; anterior sterna with deep, oval, median excava- 

 tions. Genus Geophilus. 



Genus Mecistocephalus Newport. 



Mecistocephalus NEWPORT, Proc. Zool. Soc. London, cxix, p. 178, 1842. 

 COOK, Proc. U. S. Nat. Mus., xvm, p. 60, 1895. 



A genus of circumpolar distribution. It is often treated merely as a 

 very distinct species of Geophilus, but may prove not to be monotypic. 



MECISTOCEPHALUS ATTENUATUS (Say). 



Geophilus attenuatus SAY, Jour. Phila. Acad., II, p. 114, 1821. 



Geophilus ferrugineus C. L. KOCH, Deutschl. Crust. Myr. u. Arach., heft ill 



1835- 



Pachymerium ferrugineum C. L. KOCH, System der Myriapoden, p. 187, 1847. 



Mecistocephalus ferrugineus NEWPORT, Cat. Myr. Brit. Museum, p. 81, 1856. 



Mecistocephalus attenuatus COOK, Proc. U. S. Nat. Mus., xvm, p. 60, 1895. 



In size, color, and habit this species has a gross similarity to Geo- 

 philus alaskanus, described below, but detailed comparison will show 

 many striking differences. The femur and claw of the prehensorial 

 legs are armed with denticules, and the prehensorial sternum is without 



