WOOD, PHYLOGEXY OF CERTAIN CERITHIID^ 15 



whorl changes from an obtuse angle to one both of whose sides stand at 

 angles of about 45° with the axis of the shell. This tendency increases 

 until, on the body whorl, the lower primary spiral is inconspicuous, and 

 the upper forms the most projecting portion of the strong nodes into 

 which the ribs have become contracted. The sub-sutural ridge above 

 described is, on this volution, raised at short intervals into a row of 

 smaller nodes, and on the lower portion of the body whorl there are three 

 strong nodose ridges formed, like the sub-sutural ridge, of groups of fine 

 spirals. On the under side of the body whorl ribs and nodes are nearly 

 obliterated along the surface upon which the animal rested when with- 

 drawn into its shell ; but just beyond this area, on the side of the volution 

 opposite the outer lip, the surface is raised into a strong varix. 



The aperture is oval, with a strong posterior tooth. The outer lip is 

 slightly flaring, with its margin crenulated by the spirals of the outer 

 surface. The lower portion of the outer lip grows more rapidly than the 

 upper portion, and the lowest of the nodose ridges is produced into a 

 toothlike process which, in some individuals, crosses the opening of the 

 anterior canal. The length of this process varies considerably in differ- 

 ent specimens of the species. The inner lip has a strong callus. The 

 anterior canal is long and comparatively narrow. 



Horizon and localities : Recent. Red Sea and Indian Ocean. 

 No. 20124, Columbia University collection. 



EE:\rARKs: CerWiium tuberosum is especially well adapted to serve as 

 a type of the group of shells to which it belongs, since it is a retarded 

 form passing through the various stages in its development slowly and 

 retaining primitive characteristics until a late period of its life. 



Cerithium ? nodulosum Bruguicre 

 Plate III, fig. 5 ; plate iv, figs. 4, 5. 



1792. Cerithium nodulosum BBUGUifeRE, Hist, naturelle des Vers, Encycl. M6th., 

 I, pt. 2, 478. 



1887. Cerithium. nodnJosum Tryon, Manual of Conch., IX, 122, pi. 19, figs. 13, 

 14; pi. 20, fig. 15. 



1898. Cerithium nodulosum Kobelt, Syst. Conch.-Cablnet von Martini u. Chem- 

 nitz, Bd. I, Abth. 26, 7G. pi. 15, fig. 1. 



1906. Cerithium nodulosum Cossmann, Essais de Paleoconch. Comp., VII, 66, 



Measurements : Length, 95 mm. ; greatest diameter, 47 mm. ; apical angle, 

 37° ; sutural angle, 84°. 



Color : Grayish white, more or less closely covered with Interrupted bands 

 and patches of dark brown. 



