204 



CERION, GROUP V. 



figure of striatelia of Guerin's plate 6, f. 12, but that has a parietal 

 tooth. 



This species seems allied to C. weinlandi, agrestinum, etc., of the 

 Bahamas, and may perhaps be no Cuban shell. 



V. Group of C. maritimum. 



Pinguitia MAYNARD, Contrib. to Sci., iii, p. 330, for " S. dimi- 

 diatia." 



Rather large, stout, cylindric species, ribbed, rib-striate or smooth, 

 the sutures but slightly impressed ; the parietal tooth usually short 

 (but sometimes lengthened), characteristic of Cuba, especially the 

 north coast. 



Many of the species of tins group have a smooth and a ribbed 

 form. The parietal tooth is usually short, but in some specimens of 

 certain species it continues inward to a dorsal position. This is the 

 case with the example of C. maritimum figured on pi. 30, fig. 74. 

 These long-toothed forms seem to differ in no other respect from the 

 normal short-toothed examples of the same species. Two species, 

 C. longidens and C. hyperlissum, seem to be constantly long-toothed. 



The general relationships of the species may be expressed dia- 

 grammatically. Names in italic type pertain to smooth, the others 

 to sculptured forms. 



vulneratum- 



politum 

 maisianum" 



dimidiatum 



I 



torrei 



ornatum 



I 



sagraianum 

 hologlyptum 



multicosta, incrassatum 



maritimum- 

 subltzvigatum 



1 



incanum 



-hyperlissum, longidens 



The species are all variable, impossible to limit by hard-and-fast 

 diagnoses. In a few forms, especially the extreme proteus form of 

 C. dimidiatum, some incised spiral lines are developed a feature 

 culminating in the allied group of C. scalarinum. The key below is 



