MOLLUSCA OF THE ' CHALLENGER ' EXPEDITION". 693 



List of Genera and Species. 



7. Basilissa oxytropis, W. 



1. Trochus (Gibbula) glyptus, W. 



2. T, (Ziziphinus) stirophorus, W. 



3. T. ( ) tiara, W. 



4. T. ( ) transenna, W. 



5. T. (Margarita) brychius, W. 



6. T. ( ) charopus, W. 



7. T. ( ) pompholugotus, W. 



8. T. ( ) lima, W. 



9. T. ( ) feglees, W. 



10. Trochus ( Margarita) clavatus, W. 



11. T. ( )rhysus, jy. 



12. T. ( ) infundibulum, W. 



13. T. ( ) pachy chiles, W. 



14. T. ( ) azorensis, W. 



15. T. ( ) dnopherus, W. 



16. T. ( ?) scintillans, W. 



1. Turbo (Calcar) henicus, W, 



2. T. transenna, W. 



3. T. (CoUonia) indutus, W. 



7. Basilissa oxtteopis, W. 



St. 344. April 3, 1876. Ascension Island. 420 fms. Hard 

 ground. 2 young specimens. 



Shell. — Small, liigh, conical, scalar, with a sharp, expressed carina 

 at the periphery and a second carina above, angulating the whorls. 

 Sculpture. There are a few close-set slight spirals on the edge of 

 the flat base ; there are many not close-set, flexuous, longitudinal 

 ribs above the periphery, but on the base merely lines of growth. 

 Tliese ribs in crossing the upper carina form small sharp-pointed 

 tubercles, of which there is also a trace on the lower carina. 

 The superior sinus lies just above the upper carina, the basal 

 sinus toward the middle of the base : both are well marked. The 

 apex is small and flat, the smooth embryonic 1^ whorl hardly 

 rising at all. The whorls are of slow increase. The pillar is 

 perpendicular, with a strong rounded sinus which corresponds to a 

 swelling within the umbilicus. The umbilicus is not large, but deep, 

 funnel-shaped, with a puckered sharp edge. In both specimens 

 there are 5^ whorls to a height of 0'05 and a breadth of 0'055. 



This species slightly resembles J3. alta, W., var. oxytoma, "W., 

 but is more depressed, the carina is sharper and is double, and 

 the longitudinal ribs are very much stronger. Than JB. costidata, 

 W., this species is smaller, higher, more conical, and it is scalar ; 

 the Avhorls are more carinated above, and the peripheral carina 

 is much more projecting ; the apex is minuter and sharper, though 

 the embryonic whorl is less raised, the base is smooth but for 

 the marginal spirals ; the umbilicus is smaller. 



Before leaving this genus I may add that A, Adams's subgenus 

 of ForsJcdllia (Gibbula) is quite distinct. In it " the last whorl 

 has a conspicuous groove at the periphery " according to his de- 

 finition ; but that is* a spiral farrow formed by an impressed fold 

 of the shell- wall in each successive whorl — not a sinus in the edge 



