1905.] 



NATURAL SCIENCES OF PHILADELPHIA. 



787 



ON SOME PACIFIC CERITHIID^. 



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



Fig. 1. C. thaanunii. 



Two species described in these Proceedings, p. .576, are now figured, 

 C. thaanumi and C. hawaiense, and two others are described. 

 Cerithium thaanumi P. and V. Fig. l. 



Besides the typical form of this species, 

 which measures about 12 to 14 mm. long, 

 there is a very small form, with nearly the 

 same shape and sculpture. Specimens 

 measure from length 7.8, diam. 2.5 mm., 

 to length 6, diam. 2 mm. 

 This form is also from Hilo, Hawaii, found by Mr. D. Thaanum. 

 CeritMum hawaiense P. and V. Fig. 2. 



Hilo, Hawaii. See p. 576. 

 Cerithium voyi n. sp. Fig. 3. 



Shell solid, turreted, acuminate above, the lateral 

 outlines slightly convex below, straight above. White. 

 Varices very low and inconspicuous, somewhat more 

 than two on each of the whorls of the upper half of 

 the spire; one low wide one on the last whorl opposite 

 the lip. Surface nearly smooth to the eye, showing 

 under the lens a dense sculpture of finer and coarser 

 spiral threads, the coarser ones spaced, one or two 

 near the periphery somewhat granose; the earlier 

 whorls of the spire are coarsely plicate longitudinally, 

 and crossed by three coarse cords ; this sculpture gradually becoming 



weaker below. Wliorls about 12 

 (the nucleus lost), but slightly 

 convex, the later ones a little con- 

 stricted below the suture, the last 

 whorl swollen behind the lip, pro- 

 duced in a very short canal in 

 T?„ o n ■ front. Aperture oval, acuminate 



i. Iff* o. O . VOljlj, 



above; basal notch deep and 

 open, inner lip calloused, having a callous ridge above. 



Fig. 2. 

 C hawaiiense. 



