CALLIOSTOMA. 345 



lowest three rows are much closer together, but project a little, 

 especially the center and largest row of the three. On the base there 

 are about nine less strongly tuberculated spiral threads with feebler 

 threads between, these intermediate threads becoming feebler towards 

 the center. The tubercles are smooth and polished, but the whole inter- 

 vening surface is sharply fretted with fine oblique puckerings. Color 

 white, beautifully flecked above with grayish-purple patches, and 

 closely spotted with purplish-pink on the base. Spire high and sharp 

 pointed, its concavely conical slope being slightly broken at the 

 sutures by the projection of the two superior rows of tubercles. 

 Whorls about 10, flat and of very regular increase. Suture slight, 

 but distinct, being defined by the slight carinal spiral above, and the 

 double row of large tubercles below. Mouth rather small, square, and 

 very oblique. Outer lip sharp but strong. Inner lip strengthened 

 internally by a buttress of porcelaneous nacre, which ends abruptly 

 towards the point of the pillar, forming a tooth. The pillar, beveled 

 off to a sharp edge, is pressed back on the umbilicus, which it com- 

 pletely closes, leaving only a central depression and a post-columellar 

 furrow. Operculum thin, yellow, normal. 



Alt. -64, diam. '58 inch. ( Watson.) 



This species very much resembles Trochus decoratus, Phil., but 

 that species is more highly narrowly conical, is flatter on the base, 

 and the whole system of 'spirals is different. In Trochus decoratus 

 also the earlier whorls are simply spiralled ; here the spirals are 

 cross-hatched. Trochus nobilis, Phil., is much larger, is flatter on the 

 base, and is not so closely spiralled. Trochus euglypttts, Ad., has the 

 whorls much rounder. ( Watson.) 



Arrou Is., S. W. of Papua. 



Trochus (Ziziphinus) arruensis WATSON, Journ. Linn. Soc. London, 

 vol. 15, p. 91 ; Challenger Report, Gasteropoda, p. 57, t. 6, f. 5. 



C. TRANSEXNA Watson. PI. 17, fig. 28. 



Shell small, conical, high, carinated, inflated on the base, thin, 

 sculptured, yellowish with small ruddy spots. Sculpture : spirals 

 close to the suture is a row of disconnected beads, between this and 

 the carina are three rows of appressed beads, of which the highest 

 is the weakest ; these four rows are parted from one another by 

 furrows, each of which is a little broader than the thread above it ; 

 the carina also consists of a row of appressed beads ; it is stronger 

 than the other beads both in breadth and height, and the furrow 

 above it is a little broader and deeper than the rest. On the base 



