34 ANNALS NEW YORK ACADEMY OF SCIENCES 



Measurements : Length, 63.7 mm. ; greatest diameter, 21.4 mm. ; apical 

 angle, 26.5°, changing to 23° on the twelfth volution ; sutural angle, 88°. 



CoLOB : Background of bluish white, marked by numerous spiral bands of 

 reddish brown, which on the young shell is deepest in the grooves between 

 the spirals, but on the later and adult whorls irregular patches of color cover 

 most of the surface. 



The only specimen studied which retains the protoconch is somewhat 

 worn at the apex, but the protoconch appears to be like that of Cerithium 

 adansoni. The second and third volutions are so similar as to be well 

 illustrated by the drawings of these two whorls on C. adansoni (plate iii, 

 figs. 3, -i), but the shell at this age is about twice the size of C. adansoni 

 at the same age. The fourth volution is like that of C. adansoni, except 

 that about every third rib is much larger, forming a strong varix. These 

 varices occur at gradually wider intervals up to the eleventh volution, 

 when they disappear from the specimen described. The presence of 

 varices is a variable feature, since in a series of specimens otherwise sim- 

 ilar the varices are more prominent and persist for a longer time on some 

 specimens than on others. Except for the presence of varices, the surface 

 ornamentation is like that of Cerithium tuberosum to the seventh volu- 

 tion, when small nodes appear on the sub-sutural band, one at the end of 

 each rib. Beginning with the ninth volution, the lower of the two pri- 

 mary spirals becomes gradually less prominent and the ribs become less 

 well marked, until on the twelfth volution the upper of the two primary 

 spirals only is prominent, forming a row of nodes slightly above the mid- 

 dle of the volution. The ribs, as such, have disappeared, being replaced 

 by the two rows of nodes. Spirals of secondary and higher orders in- 

 crease rapidly in number, and on the later whorls the finest spirals become 

 confluent, producing broad, flattened bands, with extremely narrow de- 

 pressions between them. On the body volution below the lower row of 

 strong nodes from three to five large spirals are faintly nodose. 



The aperture is elongate oval, with a distinct but not very prominent 

 tooth defining the posterior canal. The outer lip is slightly flaring and 

 shows faint crenulations. The callus of the inner lip is thin. The an- 

 terior canal is wide and short, with its margin slightly reflexed. 



Horizon and localities : Recent. Mediterranean Sea. west coast of Africa, 

 and southward to Senegal. 



No. 20137, Columbia University collection. 



Eemarks : Individuals of this species var\^ somewhat in the width of 

 the apical angle, in the strength and spacing of the nodes, and the extent 

 to which the fine spirals coalesce and become flattened. At present the 



