WOOD, PHYLOGENY OF CERTAIN CERITHIIDM 43 



The mutation litharium evidently belongs to the same phyletic series 

 as the species to which it is related, differing only in minor features of 

 the ornamentation, such as more prominent nodes and additional rows of 

 fine beading. 



CeritMum algicola Adams and C. muscarum Say, from the character 

 of their apertures and the general appearance of the shells, seem to be 

 related to this group, but in the absence of specimens and with very im- 

 perfect figures, it is impossible to be certain of their position. 



D. MIOCENIC SPECIES 



1. Cerithium. 



So far as can be determined from the literature, the Miocenic of the 

 Eastern Hemisphere furnishes few specimens of the Cerithium tuberosum 

 group. This is due doubtless to lack of preservation, rather than to a 

 paucity of species existing during that period. 



Cerithium hronni Partsch, of the Miocenic of the Vienna Basin, may 

 possibly belong here. [See Hornes and Partsch, 1856, plate 42, figs. 

 12a, &.] The figure, which gives no clue to the ornamentation of the 

 young shell, is insufficient evidence for placing the shell definitely, but 

 the aperture corresponds with that of C. tuberosum, and the ornamenta- 

 tion of the adult is similar in type to that of other species of Cerithium 

 sens. str. 



An unnamed variety of G. crenatum Brocchi is mentioned by Hornes 

 and Partsch [1856, p. 409] as occurring in the Miocenic of the Vienna 

 Basin. According to their figures [loc. cit., plate 42, figs. 13, 14], the 

 shell has the adult characteristics of this group, but the features of the 

 young shell cannot be determined from the figures. 



Cerithium mediterraneum, described with recent species of Cerithium, 

 is recorded by Hornes and Partsch [1856, p. 393] from the Miocenic 

 of the Vienna Basin. 



Cerithium calculosum Basterot 



1825. CeritMum calculosum Basterot, Mem. geol. sur les environs de Bor- 

 deaux, p. 58, pi. 3, fig. 5. 



Measurements : Length. 29.8 mm. ; greatest diameter, 14.1 mm. ; apical 

 angle. 37.2° ; sutural angle. 79.3°. 



The protoconch is absent from this shell, but the youngest volution 

 preserved is probably the first beyond the protoconch, and it is 1 mm. in 

 diameter. This volution is ornamented by ribs and two equal spirals. 



