PHYLOGENY OF FUSUS AND ITS ALLIES. 135 



RHOPALITHES* gen. nov. 



(poTzn/ov^ a club; /lOar^ stone.) 



Shell fusiform with a fusoid protoconch, consisting of a smooth 

 erect portion, of about a whorl or over, and a vertically ribbed portion, 

 with the fine smooth ribs widely separated. The conch consists of 

 ribbed and spirally striate whorls, which are rather closely coiled, 

 followed in the more accelerated species by smooth whorls, which gen- 

 erally develop the Clavilithoid shelf. The columella is furnished with 

 two or more oblique plications. 



Disfribufion: Eocene of Paris Basin ; Adour basin ; Northern Italy, 

 etc. 



Genotype: Fnsiis nocu Lamarck. 



RHOPALITHES RUGOIDES sp. nov. 



(Plate IX, figs. 9"i2.) (Type Plate IX, fig. lo and text fig. 20.) 

 1837. Fitsiis rugosus var. Deshayes, Coq. Foss. Env. Paris, pi. 75, figs. 10, 11. 



The protoconch of this species is fusoid, obliquely erect and con- 

 sists of a volution and a half. The greater portion is smooth, but 

 toward the end it is marked by a few fairly strong smooth ribs which 

 are several times their width apart. There are no spirals between the 

 ribs. The protoconch ends in a marked varix, and there is a pronounced 

 change in convexity and ornamentation. 



The conch begins wath strongly ribbed and spirally striate whorls, 

 on which the ribs are widely separated. The whorls 

 embrace about one third or a little more, thus producing 

 a very depressed spire. A considerable flattening of 

 the shoulder and a strong peripheral angulation results. 

 The ribs increase in strength toward the periphery 

 where two of the spirals are strong. These are soon 

 reenforced by a third, and all three produce blunt cusps ^^^- ^^- ^^'^' 



at the intersections with the ribs. In the adult or P<^}yhes ru- 



... 1111 • ,1 goides, showing 



epliebic stage the whorls become agam more rounded , , 



'^ *= ^ . protoconch. 



though the shoulder is still tlattcncd, the ribs are round (x 10 M C Z. 

 and obtuse, and a faint subsutural band exists, indicat- 27,777.) (See 

 ing a posterior canal. Two w^ell-marked plications pi. ix, fig. 10.) 

 occur on the columella. 



This species is the parallel of Claz'ilithes rugosus, with which it is 

 commonly united. While generically distinct it shares wnth C. rugosus 

 the specific characteristics and hence is to be regarded as the rugosus 

 type of this generic series. 



Localities: Paris Basin (M. C. Z. 27776, 2yy'/'/, Bronn, 1376, Duval; 

 27780 Koninck) ; Grignon, (M. Z. 27779, Duval) ; Ully, St. Georges 

 (Acad. Sci. 8027) ; Damery (Am. Mus. Nat. Hist.). 



Horison: Eocene (Middle, Cossmann). 



Additional Remarks. — From the beginning of the conch the whorls 

 are marked by strong vertical ribs which bulge at the center where the 



* Rhopalolithes would be more satisfactory to purists but is less euphonious. 



