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Trochus (Monodonta) instrtctus. Testa parva, elevata, 

 ovato-conica, arete perforata, albida et maculis dilute rufis prope 

 suturam picta : spira anfr. 5, convexiusculis, sub-imbricatis, 

 sutura profunda canaliformi sejunctis, liris acutis ubique cinctis, 

 interspatiis concinne clathratis : basis convexa : apertura oblique 

 semicircularis ; columella acuta, obliqua, in dentem terminante ; 

 labro incrassato, intus sulcato, juxta columellam rugoso et emar- 

 ginato. Long, f, lat. y 3 ^ poll. Hab. Pacific Islands. 



Trochus (Monodonta) atropurpureus. Testa parva, depressa, 

 ovato-conica, atropurpurea, liris granulosis ubique cincta : spira 

 anfr. 5-6, ultimo subangulato : basis convexiuscula, late per- 

 forata ; umbilico cavernoso, limine acuto, denticulato, prope colu- 

 mellam interrupto: apertura circularis ; columella obliqua, acuta, 

 antice dentata, emarginata; labro albo et nigro articulato, intus 

 sulcato ; fauce margaritaceo. Alt. T 2 ^, lat. T 3 ^ poll. Habitat, 

 Tutuilla, Navigator Islands. 



Allied to T. pharaonis and T. canaliculata, in its habitus and 

 umbilicus, but more like T. corallinus in size and general charac- 

 ters. Its uniform color and granulation, toothed margin of the 

 umbilic, with the conspicuous tooth above, are its characters. 



Trochus (Monodonta) rotellinus. Testa parva, solida, len- 

 ticularis, nitida, fissura latebrosa perforata, dilute incarnata, 

 flammulis flexuosis saturatioribus, et seriebus duobus transversis 

 macularum fuscarum variegata : spira anfr. 5, convexiusculis: 

 apertura parva, subcircularis ; columella perobliqua, arcuata pos- 

 tice ab anfractu sejuncta, antice in dentem acutum terminante ; 

 labro prope dentem quasi emarginato. Diam. §, alt. -J poll. 

 Hab. Mangsi Island. 



This curious little shell would at first be taken by its form, 

 polish, and color, for a Rotella, while the notch of the aperture 

 resembles that of Buccinum neriteum. But its umbilic and col- 

 umella place it with Monodonta, or more properly in that sub- 

 division of Trochus named Clanculus by Montfort. 



Trochus tantillus. Testa minuta, conico-discoidea, flavido- 

 cinerea, lineis radiantibus flexuosis fuscis picta : spira depressa, 

 anfr. 4-5 angulatis, ultimo ad peripheriam dilatato, acuto: basis 

 convexiuscula, perforata, flavida, liris duabus concentricis pro- 



