PHYLOGENY OF FUSUS AND ITS ALLIES. 121 



CLAVILITHES PARISIENSIS (Mayer-Eymar). 



In the British Eocene. 

 (Plate XIV, figs. 7 and 9.) 



So far as I am able to judge from the limited amount of material in 

 my hands, this species, while represented in the British Eocene, did not 

 attain its normal development as found in the specimens from the Paris 

 Basin. It is perfectly possible, as far as my observations go, to dis- 

 tinguish the Hampshire basin specimens from those of the Paris Basin, 

 even though we overlook the difference in color. This is probably to be 

 correlated with difference in facies between the two regions, which 

 must have caused an effective separation of the two faunal provinces 

 even though no other barrier existed. 



In fig. 4. pi. XIV, is shown an immature specimen which may belong 

 to this species. The protoconch is not widely different from that 

 of the Parisian specimens, though the apex is less depressed than in 

 those from the Calcaire Grossier. There are something over four 

 volutions, after which the spiralled and ribbed conch begins. The 

 riigosiis stage is short, followed by a pronounced danicriaccnsis stage. 

 Before the disappearance of the spirals a thickening of the suture 

 occurs which marks the beginning of the sutural shelf. The contour 

 of the whorl changes but slightly, still it becomes progressively less 

 convex. In this and in specimen fig. 3 of the same plate in which the 

 riigosiis stage is more pronounced, is a suggestion of the tiibcrcitlosiis 

 characteristics, from the appearance of a shelf, while the whorl is 

 still of a convex contour. This is particularly the case in fig. 3, where 

 the strong ntgosus characters give the nodulose appearance so char- 

 acteristic of C. titberculostis (Desh.). The same features are shown 

 in specimen fig. i of the same plate. Here the rugosus characters 

 persist still longer, but the spirals on the ribless whorls are less pro- 

 nounced. An imperfect shelf with a substitural concavity and rounded 

 contour of whorls strongly suggests the accelerated type C. tubcrcnlosns 

 of the Paris l>asin. It would be hazardous, however, to consider the 

 present immature shells of this species, particularly since the shelf is 

 scarcely more than a thickening of the edge of the whorl, such as may 

 occur in abnormal specimens of C. conjiinctns or C. danicriaccnsis. A 

 distinct shelf does appear in the young of some specimens of C. 

 solandcri and C. longccvns, while the contour is still convex. 



A specimen from the Barton beds, Hampshire, has the protoconch 

 and early whorls of the conch broken away (pi. XI\', fig. 7), About 

 two ribbed volutions occur followed by one which has the characters 

 of C. danicriaccnsis, being rounded and spirally striate. This is fol- 

 lowed by a whorl in the con j it net us stage and one in which a cylindrical 

 form and a siUtu-al shelf occur, the latter, however, not being fiat, but 



