PIIYLOGENY OF FUSUS AND ITS ALLIES. Ill 



Murcx longccviis (Sol. fig. 93). (See pi. XIV, figs. 5 and 6, and 

 pi. XV, figs. I and 2.) It is not improbable, however, that the young 

 specimen of Solander's figure 37 may prove to be the young of C. 

 longcvvus (Solander) not Lamarck (pi. XIV, fig. 8). 



This leaves Mayer-Eymar's name F. parisicnsis, proposed in 1877, 

 as the only available one for the type of the genus Clavilithes. This is 

 certainly a most appropriate name, since the species in its typical form 

 is unknown outside of the Paris Basin. 



In view of the uncertainty which is attached to the types of Sol- 

 ander's Miu'cx deformis, and in view of the fact that this species was 

 based on material too young to allow determination of its true specific 

 relationships, I propose to discard Solander's name deformis entirely, 

 and to apply the name C. solander i nom. nov., to the large characteristic 

 species of Clavilithes of the British Eocene. 



Description of Clavilithes parisiensis. 



The protoconch is of the normal papillose type, with minute apex, 

 and naticoid early whorls. No varix has been observed. On the 

 latter part of the smooth portion a few faint vertical plications exist. 

 Faint spirals are visible between. 



In all the broken specimens the septum appears as a funnel-shaped, 

 curved closing element of the protoconch. The septum makes about 

 a third volution, so that the tip is perhaps half a volution further within 

 the protoconch. The distal end (tip) of the septum is uniformly 

 rounded and lies free in the cavity of the protoconch with the excep- 

 tion of that portion which lies next to the columella, which is generally 

 united with the latter. The protoconch is still umbilicated at this stage. 

 There is some variation in the form and outline of the septum in dif- 

 ferent individuals. Septa have also been noticed in later portions of 

 the shell, after the normal characters of the conch have appeared. 

 Similar septa have also been observed in other species of this genus. 



The conch begins with whorls which are ribless but marked by 

 strong revolving lines or spirals. These are uniform, subequal, at 

 first closely crowded, later more and more widely separated. 



The succeeding portion varies somewhat. In one variety, which is 

 strongly accelerated, the ribs are almost obsolete, the whorls being 

 smooth, except for the spirals (pi. XI, fig. 7). In another less 

 accelerated variety, the ribs are quite strongly developed, of the 

 rugosus type, distant and bulging near the center. Intercalated spirals 

 appear in the third whorl of the conch or later. When the ribs are 

 well developed the whorls have the aspect of the young C. danieria- 

 ceiisis, from the close coiling of the volutions and the strong develop- 

 ment of spirals (pi. XI, fig. 9). 



