PHYLOGENY OF FUSUS AND ITS ALLIES. 99 



CLAVELLOFUSUS gen. nov. 



The species of this genus are generally placed under Clavilithes, and 

 all of them arc united with Clavilithes parisiensis (Mayer-Eymar) 

 (= C. dcformis (Solander) Cossmann) which is the C. longcBViis 

 (Lamarck not Solander) of most authors. Even so high an authority 

 as Mons. Cossmann refers all the species of this genus to that one 

 species of a genus which, though related to the present one, is never- 

 theless quite distinct. 



The genus is characterized by the long slender spire, the whorls of 

 which in the more primitive species rest upon each other in the manner 

 of the slender Fusi. The ribs are strong and far apart, and the proto- 

 conch consists of not more than two and a half volutions, the last one 

 of which is sparingly ribbed and the first obliquely erect as in Fitsus. 

 The whole protoconch is minute and markedly different from the coarse 

 many-whorled protoconch of Clavilithes with its depressed "naticoid" 

 apical whorl. The sutural shelf is abrupt in this genus, delimited 

 by a sharp angle, and either horizontal or sloping slightly inward. 

 The shell has considerable resemblance to the recent Cyrtulus, but 

 differs from that genus in the character of the young conch as well as 

 in the details of the protoconch. Finally Cyrtulus, the modern fuso- 

 melongenoid, is a direct descendant of the modern Fusi, while Clavello- 

 fusus, the Eocene fuso-melongenoid, appears to be a descendant of the 

 Eocene Fusi, and is unknown outside of the Paris Basin. 



Gcnotxpc: Clavellofiisus spirafus sp. nov. 



CLAVELLOFUSUS SPIRATUS sp. nov. 



(Type Plate I, fig. 23; see also Plate I, figs. 17, 20 and 26; Plate XVIII, fig. 4.) 

 The protoconch of this species has only been seen in two specimens, 

 in only one of which (Acad. Sci. 8024, Plate XVIII, fig. 4) it was 

 completely preserved. It is minute and Fusoid in its apical portion, but 

 consists of about two and a half volutions, a character never found in 

 Fusus, but characteristic of Cyrtulus. The second whorl is scarcely 

 larger than the first, and in the last portion is marked by faint vertical 

 riblets which are very obscure in the specimen illustrated, but in a speci- 

 men in the collection of the Museum of Comparative Zoology (1099) 

 these vertical riblets are better shown though still faint. They are thin 

 and smooth. There is no final varix, but the protoconch stops abruptly 

 and the ribbed conch begins as abruptly. In one specimen (M. C. Z. 

 1097) faint revolving spirals are shown on what appears to be the final 

 portion of the protoconch ; these cease abruptly and the coarse-ribbed 

 conch begins as abruptly. The protoconch appears to be umbilicated, 

 the umbilicus disappearing on the completion of the protoconch. In the 

 illustrated specimen a few strong vertical riblets occur toward the end 

 of the protoconch. They are rather distant and are followed by the 



