50 



b. Valves elongate-cuneiform. 

 Hiatus, equalling the whole length of the shell, apertissima, impressa, 

 lamellosa, Riippellii, spathulata, Stimpsonii, 

 t enera. 

 " nearly the entire length of the shell, cucullata, dif fie ills, 



interrupta. 

 ' ' about two-thirds the length of the shell, indistincta, Philippi- 

 nensis. 



13. R. apertissima, Deshayes, sp. 



Gastrochasna apertissima, Deshayes, Zool. Proc. p. 326, 1854. 



Rocellaria apertissima, H. and A. Adams, Genera, ii. p. 336, 1856. 

 Description. — " R. testa elongata, cuneiformi, inflata, tenui, fragili, per 

 totam altitudinem testa antice inferneque hiantissima, alba, tenui, pellucida, 

 antice brevissima, margine inferiore fere recto, posteriore obtuso, convexo, 

 superiore paulo obliquo ; valvis tenuissime striatis, striis in latere antico 

 transversalibus, in medio secundum lineam obliquam fractis, in area superiore 

 armatis, pluribus majoribus, subsequidistantibus ; ligamento angusto, elongato, 

 nigrescente. ' ' — Deshayes. 



Hab.— Philippines. Coll. Cuming. 



14. R. cucullata, Deshayes, sp. 



Gastrochasna cucullata, Deshayes, Zool. Proc. p. 329, 1854. 

 Rocellaria cucullata, H. and A. Adams, Genera, ii. p. 336, 1856. 



Description. — " R. testa elongato-cuneif ormi, tenui, alba, fragili, subcretacea, 

 extremitate antica brevissima, postica compressa, dilatata, spathuliformi, 

 antice inferneque oblique hiante, apertura lateraliter coarctata, fere totam 

 longitudinem testa? sequante, latere antico angusto, incumbente, cucullato ; 

 valvis extus in tres areas divisis, prima antica obsolete striata, mediana 

 latiore, irregulariter arcuatim striato-rugosa, tertia circa ligamentum angus- 

 tiore, hevigata, ; umbonibus tumidulis, terminalibus ; ligamento satis promi- 

 nulo, elongato, fusco." — Deshayes. 



Hab. — West Indies. Coll. Cuming. 



15. R. difficilis, Deshayes, sp. 



Gastrochasna difficilis, Deshayes, Zool. Proc. Lond. p. 328, 1854. 

 Rocellaria difficilis, H. and A. Adams, Genera, ii. p. 336, 1856. 

 Description. — " R. testa elongato-transversa, ovata, cuneiformi, compres- 

 siuscula, oblique longe hiante, hiatu ovato-oblongo, inferne attenuato, fere 

 totam longitudinem testae sequante ; valvis. trapezoidalibus, tenae striatis; 

 striis tenuissimis, erectis, angustissimis, in latere antico con ertioribus ; um- 

 bonibus minimis ; latere antico brevissimo, recto ; ligamento elongato, rufo, 

 angusto." — Deshayes. 



Hab. — Western India. Coll. Cuming. 



16. R. impressa, Deshayes, sp. 



Gastrochasna impressa, Deshayes, Zool. Proc. p. 327, 1854. 



Rocellaria impressa, H. and A. Adams, Genera, ii. p. 336, 1856. 

 Description. — " R. testa, elongato-cuneiformi, subovata, inflata, antice in- 

 ferneque amplissime aperta ; hiatu totam longitudinem testae sequante, mar- 

 gine lateraliter oblique arcuato, antice angusto ; valvis tenuibus, subtrape- 

 zoidalibus, in medio sulco vix impresso bipartitis, parte antica tenue trans- 

 versim striata, striis in sulco subfractis, parte postica arcuatim et irregulariter 

 sulcato-striata, in latere postico striis oblique ascendentibus ; umbonibus 

 tumidulis, postice obtuse subangulatis, fere terminalibus ; ligamento angus- 

 tissime, elongato, partim immerso." — Deshayes. 

 Hab. ? Coll. Cuming. 



17. R. indistincta, Deshayes, sp. 



Gastrochasna indistincta, Deshayes, Zool. Proc. p. 328, 1854. 



