28 A:^[NALS new YORK ACADEMY OF SCIENCES 



Eemaeks : This shell is distinguislied from all members of the Ceri- 

 thium columna group by the strong and regular variation in the width of 

 the spirals to correspond with their order of introduction. The regular 

 banding in color is also a distinguishing feature. The general form of 

 the shell, its early development and the form of the aperture all indicate 

 its relationship to the C. tuberosum group. 



Cerithium album Hoinbron ct Jacques 



1842-18.53. CeritJtiniii album Hombron et Jacq., Voyage Pole Sud., V, 101, pi. 23, 



figs. 22, 23. 

 1887. Cerithium ecJiinatiim Tkyon, Manual of Conch., IX, 124, pi. 20, fig. 26, 

 1898. Ceriiliitim echiiiatiim Kobelt, Syst. Conch. -Cabinet von Martini u. Chem- 

 nitz, Bd. I. Abth. 26, 102. 



Measurements : Length, 31.4 mm. : greatest diameter, 17.3 mm. ; apical 

 angle, 52.5°, changing abruptly to 23° on the last two volutions ; sutural angle, 

 76.5°. 



Color : White or cream white with occasional streaks of dark brown. 



Youngest volution, 3 mm. in diameter, bearing the two strong spirals 

 always found in the young stages of this group, with three intercalated 

 spirals. Fine additional spirals are present on the shoulder and the lower 

 slopes of the whorl. The ribs are numerous and nearly as wide as the 

 spaces between them. Fine spirals are rapidly introduced, becoming so 

 crowded below the suture that they form a broad sub-sutural band which, 

 unlike that of Cerithium tuberosum, retains the slope of the remainder 

 of the shoulder. On the fifth volution preserved, which is probably the 

 ninth of a complete shell, this sub-sutural band breaks up into a row of 

 small nodes, and the ribs become ill-denfined, giving 'place to a row of 

 strong nodes on the upper of the two primary spirals. The angle of the 

 shoulder, except in the youngest stages, is very wide, and on the body 

 volution it disappears altogether, being replaced by strongly nodose 

 spirals, of which there are five on this volution with fine rows of nodes 

 between them. 



The aperture is oval, with a well-developed posterior tooth and short, 

 oblique anterior canal. The outer lip is strongly fluted, and the callus of 

 the inner lip is narrow. 



Horizon and locality: Recent. Baker's Island, Pacific Ocean. 

 No. 20133, Columbia University collection. 



Eemaeks : This species has been considered synonymous with Cerith- 

 ium echinatum, but it differs from the latter species in several important 

 respects. Beyond the young stages, the shoulder of C. album is never 



