BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
Geological distribution. —Stampian, environs of Paris (Canu); Helvetian of 
Touraine (Collection Canu); Astian of England (Busk). 
Habitat .—Arctic Ocean: Franz Josef Land (16-205 meters) (Waters), Barentz 
Sea. Eastern Atlantic: English Channel, North Sea off Germany, Denmark, 
England, Norway (19-24 meters), Gulf of Gascony (17-180 meters), jnouth of the 
Tagus, Cape Verde Islands. Western Atlantic: Woods Hole (3-30 meters), Panama. 
This species lives principally at the mouth of streams and large rivers. 
Plesiotypes. —Cat. Nos. 68396-68398, U.S.N.M. 
Fig. 1.—Genera of the family Electrinidae D’Orbigny, 1851. 
A. Eleclra Lamouroux, 1816. E. pilosa Linnaeus, 1758, X 46. Recent. 
B. Membranipora Blainville, 1834. M. membranacea Linnaeus, 1758, X 15 (left) and M. tuberculata 
Bose, 1802, X 20. Recent. 
C. Herpetopora Lang, 1914. H. anglica Lang, 1914, X 27, Cretaceous (after Lang, 1914). 
D. Mystriopora Lang, 1915. M. mockleri Lang, 1915, X 26. Cretaceous of England. 
E. Pyripora D’Orbigny, 1852. P. calenularia Jameson, 1914, X 25. Recent. (A E., after Hincks, 
1880.) 
F. Heterooecium Hincks, 1892. H. amplectens Hincks, 1892, X 55. Recent. (After Levinsen, 
1909.) 
