WOOD, PHYLOGEXY OF CERTAIN CERITHIID^ 33 



C. echinatum. As compared with C. graciliforme, therefore, C. echina- 

 tum is accelerated in the acquisition of the sliarply 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 SlieJls closely related to the Cerithium 



tuberosum Group 



Genus Vulgocerithium Cossmann 

 190(5. Vi(l<;(jccritJiiitm Cossmann Essais de Paleoconeh. Comp., VII, 77. 



Genotype Cerithiuni vulgatmn Bruguiere : 



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

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

 tuberosum. The adult differs in a nuniV)er of rather constant features 

 and therefore may be considered distinct. The surface ornamentation 

 of the adult shell is characterized ])y the development of ribs or large 

 nodes, a sub-sutural row 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 reflexed. 



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 Brugiiicrc 



17.57. Le Goiniiier Adanson. Histoire Naturelle du Senegal. 1757. p. 1.56. pi. 10. 

 fig. 3. 



1792. Cerithium iiiIiidtiiDi Bruguiere. Dictioiiaire. No. 13. 



f8o.5. Ceriiliimn vidr/atiim Sowerby. Tliesjuinis Conch.. II. 804. pi. 178. fig. 43; 

 pi. 179. fig. 67. 



1898. Cerithium viilfjatuDi Kobelt. Syst. Coneb. -Cabinet von Martini u. Chem- 

 nitz. Bd. I. .\hth. 26. 87. pi. 17. tigs. 1-8; pi. 18. figs. 1-4. 



1906. Viilf/ocerifhiiini viilr/atiim Coss.mann, Essais de Palgoconch. Coiup.. VII, 

 77, 



