GASTEROPODA. 191 
A pretty species of the same type as M. canaliculatus, but smaller, 
more conical, and entirely different in colour. 
Figures 225, 225 a, two views of the shell, enlarged; 225 4, details 
of the sculpture; 225c, natural size. 
Trocuus (MonoponTA) ROTELLINUS. 
Testa parva, solida, lenticularis, nitida, Jissura latebrosa perforata, di- 
lute incarnata, flammulis flexuosis saturatioribus, et seriebus duobus 
transversis macularum fuscarum variegata: spira anfractibus quin- 
que convexiusculis : apertura parva, subcircularis ; columella perob- 
liqua, arcuata, posticé ab anfractu sejuncta, anticé in dentem acutum 
terminante ; labro prope dentem quast emarginato. 
Trochus (Monodonta) rotellinus, Goutp ; Proceed. Boston Soc. Nat. 
Hist., 1. 108. April 1850. Expedition Shells, 59. 
SHELL small, solid, discoidal-lenticular, smooth, polished ; whorls 
six or less, forming a smooth, slightly convex disk above, with the 
suture very delicate; beneath nearly as convex, apparently imper- 
forate, but, on a close examination, a fissure-like perforation will be 
found, entering from the aperture in a very oblique manner: aperture 
small, nearly circular, with a mimic canal at the base: columella very 
oblique, crescentic, disjoined from the penultimate whorl, and ending 
abruptly below in a tooth, forming the margin of the basal notch: lip 
simple, pale flesh-coloured, with zigzag radiations of deeper colour, 
and also two series of small quadrate dots, one on each side of the 
periphery, the upper one continued up the spire and seen on the edge 
of the suture. 
Diameter three-eighths of an inch; axis one-fifth of an inch. 
Inhabits Mangsi Island, China Sea. Pickering. 
This curious little shell would at first be taken, by its form, lustre, 
and coloration, for a Rotella; while the notch of the aperture resem- 
bles Bucconum neriteum, but its umbilicus and columella place it with 
Monodonta. 
