8o PHYLOGENY OF FUSUS AND ITS ALLIES. 



revolving color bands, which cross the shoulder but leave practically 

 the whole of the exposed part of the body free. This is as broad as 

 the flat part of the body. Just above the suture the body recedes and 

 is colored by several brown revolvino- bands. The ribs are most 

 strongly developed on the white band. 



In slightly more advanced specimens the same coloration occurs, 

 but the nodulations on the shoulder angles become very prominent and 

 the ribs weaker on the shoulder. Intercalation is twice compound. 

 One specimen (M. C. Z. 931) shows a rerounding of the shoulders in 

 the last two whorls, the shoulder on all the whorls being less flat. At 

 the beginning of the ultimate whorls the ribs have disappeared, and 

 the shell is smooth for about half an inch in length. This is ap- 

 parently a pathologic condition. After this the normal conditions 

 appear again, but with a convex shoulder which merges with the body 

 more and more, so as to produce a uniform curvature. The angula- 

 tion remains only as a carina. The revolving color bands do not 

 occur in this specimen, but in their place vertical color bands mark 

 the ribs slightly in front of the center from the beginning of the angu- 

 lation to the end of the shell. 



In another specimen (M. C. Z. 929) old age characters are shown, 

 the ribs and shoulders having disappeared together with the color 

 bands. The whorls at the same time become round and colorless. 



Localities: Mediterranean (M. C. Z. 928, 930, 931, 932) (B. S. 229, 

 6083, 6084, 231) ; Tuscany (M. C. Z. 929) ; Morocco (M. C. Z. 933). 



13. EOCENE SPECIES GENERALLY REFERRED TO 



FUSUS. 



In the Eocene of the Gulf States of North America occur several 

 species of Fusoid shells which have all the aspect of a true Fiisiis, but 

 differ from that genus in the strikingly distinct protoconch. This is 

 closely similar to that of many species generally referred to Plenrotoma. 

 These shells are genetically related to Leznfusns, and species like 

 "Fusus" bclliis of the same geological horizon which have similar 

 protoconchs. Of these groups they represent the elongated types. 

 Their genetic relation to certain species of the heterogeneous group 

 Flcurotoina is suggested by the close similarity of protoconch and early 

 whorls. For such shells with Fusus form and Plcnrotouia protoconch 

 the name Falsifnsns is proposed. 



FALSIFUSUS gen. nov. 



Shells fusiform, with a long and slender spire, and a canal of about 

 the same length. Protoconch merging into the whorls of the conch, 

 no sharp line of demarkation being apparent. The first two whorls 



