702 EEV. E. BOOG WATSON ON TKE 



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

 numerous, and the shell is brilliant in polish and in colour, 



7. TilOCHTJS (Ma.E0AEITA) POMPHOLUGOTUS, W. (Trofj.(j)oXvyw- 



Tos, bubble-shaped.) 



St. 24. March 25, 1873. North of Culebra Island, St. Thomas, 

 Danish "West Indies. 390 fms. GloUgerina-ooze, coral, shells. 

 1 specimen. 



Sliell. — 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 veiy minute, one or two above the periphery stronger than 

 the rest ; the lowest of all is much the strongest, and defines the 

 umbilicus, within wbich the whole sculpture increases in distinct- 

 ness ; on the penultimate 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 inter- 

 mediate thread. Longitudinally these spirals and furrows are 

 crossed by much finer and sharper oblique threads, wliich in 

 general are much narrower than tlieir interstices ; but towards 

 the mouth, where all the sculpture becomes feebler, these threads 

 become extremely numerous and crowded. Colour yellowish 

 chalky white over brilliant nacre. Spire not much elevated, but 

 a little scalar. Apex eroded. Whorls 5, rounded, of rapid in- 

 crease, inflated on the base. Suture impressed near the apex, 

 while towards the mouth it becomes filled up, and is finally mar- 

 ginated, by the last whorl lapping up rather coarsely on the pre- 

 vious one. Mouth rather oblique, a little higher than it is broad, 

 slightly flattened above, and a very little angulated at the junction 

 of the outer lip to the body. Lip thin, a very little reflected on 

 the umbilicus, porcellanous on the edge, with a very slight pearly 

 marginal callus, which is continuous across the body, and nacre- 

 ous within. Umhilicus large, funnel-shaped, quickly contracting, 

 but leaving the whole inner spire visible. H. 0"38. B. 0'4, 

 least 0-33. Penultimate whorl 0-1. Mouth, height 0'23, breadth 

 0-2. 



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 T. lima, W., when, as sometimes in 

 that species, the sculpture is exceptionally obsolete ; but the 



