WOOD, PHYLOGE^'Y OF CERTAIN CERITHIID^ 45 



trace of columnellar plication was found on only one of the seven speci- 

 mens studied, and this barely distinguishable feature seems insufficient 

 ground for the establishment of a new genus. 



Cerithium calculosum, mut. globulus n. mut. 



Like Cerithium glaphyrea, C. calculosum has a variety which differs 

 from the type in having finely nodose spirals intercalated between the 

 stronger ones and in having the row of fine nodes just above the suture 

 fully exposed rather than covered by the next whorl, as in the case of 

 the original species. 



Horizon and locality : Miocenic. Martillac near Bordeaux. 

 No. 20142, Columbia University collection. 



Cerithium chipolanum Dall 



1892. Cerithium cliipolannm Dall, Trans. Wagner Free Institute of Sci., Phila.,. 

 III. pt. 2, 285. pi. 22. fig. 7. 



Measurements (Dall) : Length, 10 mm.; greatest diameter, 4.5 mm. 



A specimen of this species has not been obtainable, but a good figure 

 and description make possible the determination of its relationship with 

 a fair degree of probability. The author of the species describes four 

 spirals on each volution, and the figure shows that in the young shell two 

 of these are more prominent than the others, forming the oblique-angled 

 outline of the whorl characteristic of the Cerithium tuberosum group. 

 Later in the growth of the shell the lower of the two strong spirals be- 

 comes weaker, giving a sharply angled outline to the whorl. On the 

 body whorl two of the spirals on the shoulder increase in size, so that the 

 ornamentation of this volution consists of a shoulder with two strong 

 spirals on its slope and two below the shoulder angle. 



The aperture is of the type usual in this group, with a well-developed 

 posterior tooth and short, widely open anterior canal. 



Horizon and locality : Older Miocenic of the Chipola beds, northwest 

 Florida. 



Remarks : Dall states that C. chipolanum is not closely related to any 

 of his preceding species, which would include C. callisoma and C. gla- 

 phyrea, but he does not say in what respect the divergence is expressed, 

 unless the high development of varices mentioned is considred such a dif- 

 ference. "Varices are, however, characteristic features of Cerithium sens, 

 str. This little species is more closely coiled than the Pliocenic C. colli- 



