WOOD, PHYLOGEXY OF CERTAIN CERITHIID^ 33 



C. echinatum. As compared M'ith C. graciliforme, therefore, C. ecJiina- 

 tum is accelerated in the acquisition of the sharply angled outline of the 

 volution, but retarded in the development of nodes. 



A. marked similarity in the early development of these species is well 

 illustrated by the diagram. If a card be placed over the lower part of it 

 the eye is at once struck by the uniformity of the figures; moving the 

 card downward, differences begin to appear, becoming wider as repre- 

 sentations of the adult stages are reached. The divergence would be even 

 more marked if all the features of the shell could be indicated, instead 

 of the mere presence or absence of the five features represented. 



2. Genera and Species of Recent Shells closely related to the Cerithium 



tuberosum Group 



Genus Vulgocerithium Cossmann 

 1906. Vulgocerithium Cossmann Essais de Pal6oconch. Comp., VII, 77. 



Genotype Cerithium vulgatum Bruguieee: 



This genus is closely related to Cerithium sens. str. The early stages 

 of the genotype Cerithium vulgatum are closely similar to those of C. 

 tuberosum. The adult difi'ers in a number of rather constant features 

 and therefore may be considered distinct. The surface ornamentation 

 of the adult shell is characterized by the development of ribs or large 

 nodes, a sub-sutural roAv of smaller nodes, and by the coalescence of the 

 fine spirals into flattened bands defined by extremely narrow grooves. 

 The margin of the anterior canal is usually slightly refiexed. 



M. Cossmann's main points of difference from Cerithium sens. str. are 

 not only the elongate form of the shell and characteristic surface orna- 

 ment, but especially the form of the aperture. The absence of the more 

 rapid growth on the anterior part of the outer lip, which forms a project- 

 ing tooth in some species of Cerithium, is considered of most importance, 

 and the shorter siphonal canal and less flaring outer lip are also men- 

 tioned. 



Vulgocerithium vulgatum Bruguicre 



17.57. Le Goumier Adanson, Histoire Naturelle du S4n§gal, 1757, p. 156, pi. 10, 

 fi?. .3. 



1702. CcKithiiim rulfiatnm Bruguicre, Dictionaire. No. 13. 



1855. Cerithium vuhjainm Sowerby, Thesaurus Conch., II, 864, pi. 178, fig. 43; 

 pl. 179, fig. 67. 



1S0S. Ccrithiiihi viilfiatHm Kobeet, Syst. Conch.-Cabinet von Martini u. Chem- 

 nitz. Bd. I, Abth. 26. 87, pl. 17. figs. 1-8; pl. 18. figs. 1-4. 



IOOIk Vulgocerithium vulgatum Cossmann, Essais de Pal^conch. Comp., VII, 

 77. 



