CYPIMA. 39 



as to colour, is the superdeposit of a yellow-brown spot on, 

 or half over the white spots. This is seen even in the pale, 

 short, tumid variety named flaveola ; but in cernica, from 

 the Mauritius, no trace of this appears ; the spots are round 

 and clear. 



133. bicallosa, Gray, (f. 220, 221). — C. testa ovato-pyri- 

 formi, rubido-crocata, solida, marginata ; extremitatibus sub- 

 acuminatis, callositate conspicua munitis, ad latera obscure 

 crenulatim foveolatis ; dorso rotundo, castaneo varie macu- 

 lato et nebulato ; basi incrassata ; apertura angusta, flexuosa, ; 

 dentibus validis, super basim columellas ad extremitates 

 elongatis, labii 23 elongatis, interstitiis profunde excavatis ; 

 labio postice elevato, antice abbreviato, medio sinuatim pro- 

 ducto. 



Note. — This very rare shell is one of those that cannot be 

 put beside any other for comparison, the callosities on the 

 termino-dorsal arches, and other characters of form and 

 sculpture, being quite peculiar. It has more affinity with 

 helvola than with any other species. 



134. helvola, Linn., (f. 214-217; var. pallida, tenui, 

 f. 217). — C. testa crassa, depress!, ovata; lateribus incras- 

 satis, reflexis, crenato-foveolatis, crocato-fuscatis ; extremi- 

 tatibus plerumque violaceis, medio albescentibus ; dorso 

 fusco, ocellis numerosis albis maculisque castaneo-rubris 

 sparso, colore supra marginem saturatiore ; basi crocato- 

 fusca; apertura angusta; dentibus validis, circa 12 et 13, 

 ad extremitates super basim extensis, medio breviusculis, 

 interstitiis profunde inciso-excavatis ; labio lato. 



135. citrjna, dray, (f. 218, 219).— C. testa C. lielvolm 

 affini ; dentibus 18, et 18 parvis, interstitiis haud profundis ; 

 lateribus haud incrassatis ; extremitatibus acuminatis ; labio 

 angustato. 



Note. — Helvola and citrina. The Sandwich Island form 

 and colouring of helvola are like varieties from that locality 

 of several other species. The colouring is pale yellowish, 

 with the markings only dimly seen ; the shell is thinner, and 

 the sculpture sharper than in the common variety. Citrina 

 is fully distinguished by the shallowness of the dental inter- 

 stices, and the greater number of the teeth. The colouring 

 is also much more simple. The white cribrarious holes left 

 in the ground colouring of helvola are supplemented by 

 superimposed specks of white, which is not the case in citrina. 



