122 PHYLOGENY OF FUSUS AND ITS ALLIES. 



sloping outward. Gerontic characteristics are shown by a thickening 

 of the Up through a piling up of layers, and by the formation of a deep 

 posterior canal, as well as a slight sutural canal. 



Another adult specimen from the Bracklesham beds of New Forest, 

 Hampshire (pi. XIV^, fig. 9), shows a septum near the end of the proto- 

 conch, and an acceleration in the nepionic stage, in wdiich the non- 

 undulate spirally striate character, usually seen only in the last stages 

 preceding the conjunctus stage, makes its appearance. A few faint 

 undulations are, however, still visible in the early nepionic stage. There 

 are about three volutions, which have the form and spirals of the 

 dameriaccnsis stage, the spirals being uniform, except just below the 

 suture, where they are closely crowded. Intercalated spirals appear 

 toward the end of these volutions. 



The conjunctus stage is seen in the next whorl, which is, however, 

 soon modified by having the whorl flattened laterally and so becoming 

 cylindrical in form. This continues for a time, with an outward slop- 

 ing shoulder, giving an appearance very unlike that of the French 

 species. A strong senile feature is shown in the crowding together of 

 the last added lamell?e, making a rough terminal portion of the last 

 whorl, an irregular sutural shelf, and a pronounced posterior canal. 



This specimen represents a case of extreme acceleration, the rugosus 

 stage being practically dropped out, so that the earliest whorls of the 

 conch are in the damcriacensis stage. 



Hori::on: Bracklesham (Middle) and Barton (Upper) beds of the 

 British Eocene. 



Localities: New Forest (M. C. Z. 27767) and Barton (M. C. Z. 

 27768) ; Hampshire. 



CLAVILITHES CONJUNCTOIDES sp. nov, 

 (Plate VIII, fig. 19.) 

 General characters like C. conjunctus, but the preephebic whorls 

 strongly and coarsely ribbed and marked by spirals, and very unlike the 

 regular ribs and spirals found in the Parisian species. The ribs are 

 rather irregular and bulging in the center. The whorls embrace less 

 than is the case with British species of this genus generally. The 

 ribbed whorls are rather abruptly succeeded by smooth ones, which 

 are at first rounded, but later have their sides flattened and sloping 

 outward after the manner of C. solandcri and C. cgrcgins. A faint 

 shelf appears usually while the whorls are still round, thus showing 

 an advance upon the French species. This shell is readily distinguished 

 from the other British species by its strongly and coarsely ribbed spire. 

 This distinguishes it also from the French species, from which it also 

 differs in the loose spire with rather deeply impressed suture and the 

 sloping sides of the body-whorl. It resembles most nearly some of the 

 American species. 



