360 CALLIOSTOMA. 



iuside ; colunieDa short, vertical, arcuate above, terminating in a 

 truncation or fold-like tooth. Alt. 13, diani. 7 mill. 



Viti Islands. 



Ziziphinns venustus Dkr., Mai. BL, xviii, p. 169, 1871. 



This species has the greasiest similarity to the Mediterranean 

 C. striatum Linn. The columella is very strongly folded at the base ; 

 the color is either green or red ; on one shell before me the spire is 

 red, body-whorl greenish. In pattern of color the shells before me 

 differ little. It is possible that some forms included by me in the 

 group of C. exasperatum as synonmyms may prove to be valid species 

 of the south-west Pacific. Reeve and others report sucli forms 

 ( Vide Tr. soda Fischer ; goniostomus Mke.). Without specimens 

 from authentic localities this cannot now be decided. The specimens 

 of C. venustum before me were collected by Garreit. 



C. MARMOREUM Pease. PI. 39, fig. 33. 



Shell elongate-conical, imperfoiate, but with a groove and pit or 

 even a slight perforation at the place of the umbilicus ; rather solid ; 

 whitish, longitudinally clouded with brown or j^ink, often showing 

 white opaque scattered dots; surface polished ; sculpture consisting 

 of numerous broad flat smooth spirals, separated by impressed lines ; 

 there are seven of these flat spiral ribs on the upper surface of the 

 last whorl, the peripheral one larger; the base has numerous concen- 

 tric stride, and about 4 spaced, more impressed grooves ; spire high, 

 lateral outlines nearly straight ; whorls about 8, each one a trifle 

 convex, the last angular at the periphery ; base a little convex ; 

 apertui*e quadrate ; columella vertical, obliquely truncate at base. 



Alt. 6, diam. 4 mill. ; alt. 8, diam. 5 mill. 



Patimottts. 



Tr. marmoreus PsE., Amer. Journ. Conch, iii, p. 287, t. 24, f 9. 



This is a second Polynesian species of Calliostoma which approaches 

 very closely to Mediterranean types. It is smaller than C. venustum, 

 and less abruptly truncated at base of columella. The base of the 

 aperture is not rounded, as the figure shows, but nearly straight. 



American Species. 



The West American species fall into three groups, as follows: 



I. Shell with numerous smooth cord-like spiral riblets, group of 

 C. canaliculatum Mart. 



II. Shell thin, with numerous granulose spiral riblets, interstitial 

 liruhie few or none, group of C. annulatum Mart. 



