302 MARGARITA. 



rapid increase, the spirals on the base are very much more numerous, 

 and the shell is brilliant in polish and in color. ( Watson.) 



Kerguelen Id. ; off Cumberland Bay, 1 05 fins. 



T. (Margarita) charopus WATSON, Jour. Linn. Soc. Lond. xiv, p. 

 700 ; Challenger Gasterop., p. 78, t. 5, f. 6. Var. cceruleus, I. c. 



M. POMPHOLUGOTUS Watson. PI. 64, figs. 59. 



Shell depressedly globose, with a low turreted spire, thin, opaque,, 

 chalky, rough, umbilicate. Sculpture : There are of spirals on the 

 last whorl about forty, low, rounded, very unequal, some being very 

 minute, one or two above the periphery stronger than the rest ; the 

 lowest of all is much the strongest, and defines the umbilicus within 

 which the whole sculpture increases in distinctness ; on the penulti- 

 mate whorl there are about twelve spirals fully stronger than on the 

 last. The furrows are broader than the threads, but as they widen 

 are occupied by a minute intermediate thread. Longitudinally 

 these spirals and furrows are crossed by much finer and sharper 

 oblique threads, which in general are much narrower than their 

 interstices; but towards the mouth, where all the sculpture becomes 

 feebler, these threads become extremely numerous and crowded. 

 Color yellowish-chalky-white over brilliant nacre. Spire not much 

 elevated, but a little scalar, apex eroded. Whorls 5, rounded, of 

 rapid increase, inflated on the base. Suture impressed near the 

 apex, while towards the mouth it becomes filled up, and is finely 

 marginated, by the last whorl lapping up rather coarsely on the 

 previous one. Mouth oblique, a little higher than it is broad, slightly 

 flattened above, and a very little angulated at the insertion of the 

 outer lip. Lip thin, a very little reflected on the umbilicus, porcela- 

 neous on the edge, with a very slight pearly marginal callus, .which 

 is continuous across the body and nacreous within. Umbilicus large, 

 funnel-shaped, quickly contracting, but leaving the whole inner spire 

 visible. 



Alt. 0'38 in. diam. 0'4, least 0'33. Penultimate whorl, O'l. Mouth, 

 height 0-23, breadth 0-2. ( Watson.} 



Both in form and texture this species is extraordinarily like a 

 depressed Cyclostoma. I have given it its name, in the absence of 

 marked features, from its slight resemblance to a bubble. It has 

 some resemblance to Trochus rhina Wats., when, as sometimes 

 in that species, the sculpture is exceptionally obsolete ; but the sculpt- 



