38 ANNALS NEW YORK ACADEMY OF SCIENCES 



not begin until the seventh volution, as compared with the fourth volu- 

 tion on the preceding species. The embracing of the whorls is not so 

 close as on V. pUcatum. The adolescent and adult stages are distinguished 

 by the much smaller nodes of the present species and by the form of the 

 node, which is sharp and pointed at the apex in V. gracile, as compared 

 with the blunt but more prominent and more elongate nodes of V. pUca- 

 tum. The anterior canal also differs in being longer, narrower and 

 slightly recurved. 



Vulgocerithium adenense Sowerby 



1866. Ceritlniim adenense Sowerby. apud Reeve, Conch. Iconica, XV, No. 89. 

 1887. Cerithium adenense Tryon, Manual of Conch., IX, 124, pi. 20, fig. 30. 

 1898. Cerithium adenense Kobelt, Syst. Conch.-Cabinet von Martini u. Chem- 

 nitz, Bd. I, Abth. 26, 196, pi. 35, fig. 12. 



Measurements : Length. 2.3.2 unu. ; greatest diameter, 8.4 mm. ; apical angle, 

 .32..5°, changing to 21° on the last four volutions; sutural angle, 83.5°. 



Color : Yellowish or grayish white, with ill-defined sinuous lines of reddish 

 brown crossing the spirals. 



The apex of the shell is broken away. The youngest volution studied 

 is 1,4 mm. in diameter and has the usual two strong spirals, with one 

 intercalated spiral and one or two spirals on the shoulder. Well-developed 

 ribs cross all the spirals. The ornamentation remains of the same type, 

 with the addition of spirals for the next three volutions. On the fifth of 

 the volutions preserved a sub-sutural row of irregular, low nodes is devel- 

 oped, and the upper primary spiral forms sharp-pointed nodes where 

 crossed by ribs. On the later volutions the coarser spirals become broad 

 and flat, with fine grooves between them, and the finer spirals become 

 obsolete. The adult ornamentation is that of widely spaced ribs, which 

 are almost spinose where crossed by the upper primary spiral. The upper 

 slope of the rib is concave and the loAver slope straight or slightly convex, 

 which gives the center of the rib the appearance of an upward-pointing, 

 Ijlunt spine. There are three rows of finely nodose spirals on the lower 

 slope of the body volution. 



The aperture is elongate oval. The callus of the inner lip is moder- 

 ately thick, with a well-developed posterior tooth, and the outer lip is 

 thin. The anterior canal is short and widely open. 



Horizon and localities : Recent. Island of Karak, Persian Gulf, Gulf of 

 Aden. 



No. 20140, Columliia University collection. 



Remarks : This little species is nearest to V. viilgatum but is distin- 

 guished by the great difference in the size of the shell and the size and 



