PIIYLOGENV OF FUSUS AND ITS ALLIES. I27 



widening path-like spiral which is the most pronounced feature of C. 

 solanderi. 



The spines, which generally appear quite early, heconie imhricating 

 and coarse in the later whorls. The body whorl is semi-globular, as 

 in the gerontic specimen of C. solanderi, and the spindle and canal 

 long. A fold occurs just below the posterior canal, but becomes cov- 

 ered by the thickening of the canal. 



Localities: Hampshire, Barton clifif (M. C. Z. 1062. 1063, Lyell, 

 27763, Keeping). 



Horizon: Barton Beds, Upper Eocene. 



This and the preceding species were also referred by some of the 

 labels to the London Clay (Lower Eocene). This is probably 

 erroneous. 



No specimen of C. parisicnsis has as yet been seen, which shows 

 anything but the loss of characteristics in its gerontic stage. By the 

 loss of the shelf the species assumes again the characters peculiar to 

 the more primitive C. conjunctus. In the gerontic stage of C. solanderi 

 we have, on the other hand, a distinct addition, a new character, spines, 

 being developed in the old age of the individual. The succeeding 

 species, C. longccvus, has this newly acquired character developed to 

 the exclusion of almost all the other characteristics. The character is 

 a newly acquired one in the old age of the earlier individuals, and it 

 has not only become inherited in the succeeding species, but, in obedience 

 to the law of acceleration, has been pushed back into the youthful 

 stages of the shell. 



Xo specimen of C. subscalaris with the scalaris features in the 

 gerontic stage have as yet been seen. From analogy wnth C. solanderi, 

 and from theoretical considerations, w'e should expect to find scalaris 

 features appearing in extreme old individuals of C. subscalaris. 



There is a remarkable parallelism between the young of typical 

 species of Clavilithes, like those of the Paris Basin, and that of 

 Turbinella chipolana Dall from the Tertiary of Chipola River, Calhoun 

 County, Florida. Other species of Turbinella whose young are very 

 similar to Clavilithes are T. regina Heilprin and T. scoly>noides Dall. 

 both from the later Tertiaries of Florida. Externally scarcely any 

 difference can be seen between the young Turbinellas and the young 

 Clavilithes. The protoconch of the former is perhaps somewhat larger, 

 but that is not always the case. Often it shows a slight angularity, 

 which recalls the protoconch of "Fusus" probocidiferus. The character 

 of the ribs and spirals on the young conch are also closely similar to 

 those of young Clainlithes. The three strong columellar plications, 

 which are seen even in the young of Turbinella, and the elongated char- 

 acter of the lip, which recalls Rhopalithes nocc, are, however, pro- 

 nounced differences. In the youngest shells of Turbinella seen the 

 upper of the three plications is very weak. 



