576 PROCEEDINGS OF THE ACADEMY OF [AugUSt, 



ON TWO HAWAIIAN CERITHIID^. 



BY H. A. PILSHRY AND E. G. VANATTA. 



Cerithium thaanumi n. sp. 



Sliell slendei", turreted, with slio'htly convex outlines below, acumi- 

 nate al)ove. Brownish-white, very sparsely maculate with brown. 

 Varices very low and inconsjiicuous, two on a whorl. The last whorl 

 has a low wide varix opposite the lip, is excavated at the base, and pro- 

 duced in a short, straight anterior canal. Sculj^ture of rather coarse 

 S]:)iral cords with a smooth thread in each interval, three of the larger 

 cords on the penultimate and earlier whorls granose. Whorls 12 

 (without the nucleus), convex. Aperture small, the outer lip very 

 strongly arcuate, thin; basal notch deep, rounded and contracted. 

 T^ength 14.2, diam. 4.5, longest axis of a]:)erture without canal 3 nnii. 



Hilo, Hawaii. (Mr. D. Thaanum.) Types No. 85,855, Coll. 

 A. N. S. Phila. 



A more slender shell than C. iiesioticirm, more coarsely sculptured, 

 with convex whorls and smaller, moi'e laterally expanded aperture. 

 Cerithium hawaiense n. sp. 



Shell minute, purplish-black, the whorls of the spire carinated a 

 short distance above the suture, acutely so on the earlier whorls; 

 strongly plicate above the carina, the folds rounded, about as wide as 

 the intervals, obsolete or reduced to rip]:»les on the latter half of the 

 last whorl. There is one strong varix, usually white, on the back of 

 the last whorl; the whole surface closely striate spirally throughout. 

 Wliorls 7 or 8. the last shortly produced below. Aperture ovate, the 

 outer lip evenly arcuate; basal notch short, deep and open. Length 

 3.5, diam. 1.2 mm. 



Hilo, Hawaii. (I). Thaanum.) Types No. 90,089, Coll. A. N. S. 

 Phila. There are also specimens in the collections of D. Thaanum, 

 S. Raymond Roberts, and the Australian Museum at Sydney. 



Its more striking characters are the acute keel on the earlier whorls 

 and the regular wave-like folds above the keel. 



