wards the umbilicus, and at length I'orniing another lobe nearly 

 covering the umbilicus, whose margin is angular ; operculum 

 horny, multispiral. 



Larger, more solid, and smoother than C. auriculatum, and 

 differmg from that species in its much tliicker, revolute peritreme, 

 formnig two distinct lobes, one of wliich nearly covers the um- 

 bilicus. 



West Indies. Mtis. Cuming. 



193. Cyclostoma decussatum (Tab. Suppl. xxxi. a, f. 300 

 301), nobis. ' ' 



C. testa oblonga, pyramidah, fusca seu fusco-nigricante decus- 

 satnn^ sulcata ; apice decoUato ; anfractibus quatuor, rotundatis ; 

 sutura vaHda, creuulata ; apertura subelliptica, peritremate duplici' 

 interno tenuiusculo, sublevato, externo latiusculo, reflexo, umbili- 

 cum parvum subtegente. 



Shell oblong, pyramidal, fuscous or blackish, decussately 

 grooved, with an obtuse decollated apex ; volutions four, rounded ; 

 suture distinct, crenulated ; aperture somewhat elliptical, slightly 

 acuminated posteriorly; peritreme double, inner narrow, slightly 

 elevated, outer rather wide, reflected, partly covering the small 

 umbilicus. 



West Indies. Mus. Cuming. 



194. Cyclostoma Copanense (Tab. Suppl. xxxi. b, f. 310 

 311), nobis. ' 



C. testa acuminato-turrita (plerumque decollata), l^vi, tenuis- 

 sime striata, nitida, olivaceo-fulva ; spira elongata ; anfractibus 

 sex, rotundatis ; sutuifi distincta; apertiu-a circulari ; peritremate 

 duphci, interno tenui, angusto, porrecto, ad ultimum anfractum 

 mterrupto, externo lato, lamellari, extenso, subinflexo, ad ulti- 

 mum anfractum porrecto, emarginato, flexuoso ; umbilicJ mediocri, 

 extus carmato; operculo corneo, multispirali, lamelloso, intus 

 stylo brevi, centrali, margine incrassato. 



Shell acutely tui-reted (usually decollated), very finely lono-itu- 

 dinally striated, but smooth and somewhat shining, of an oliva- 

 ceous fulvous colour; the remaining volutions of the lengthened 

 spire after decollation are in general sLx ; they are rounded, and 

 the suture is distinct ; aperture circular, with a double peritreme 

 the inner of which is tliin, narrow and projected forward, and 

 interrupted at the last volution ; the outer is broad, lamellar 

 spreading, slightly inflected, and flexuous, notched and projected 



