188 MOLLUSCA. 
Lessoni. Its small size, minutely freckled surface, with the articu- 
lated bands of black and yellow, may mark it. 
Figures 218, 218 a, 2184, three views of the shell, enlarged ; 218 c, 
natural size. 
Trocuus spurcus (Gould). 
Testa parva, solida, globoso-conica, nitida, ubique stris volventibus exili- 
bus insculpta, oblique strigis angulatis stramineis et fuscis alternan- 
tibus variegata, prope suturam maculis quadratis quoque picta: spira 
anfractibus quatuor ad quinque ventricosis, ultimo subangulato ; 
sutura impressa: basis concavo-conica, imperforata vel arcte umlih- 
cata: apertura perobliqua, circularis ; columella arcuata ; labro acuto, 
stmplict ; fauce submargaritaced. 
Trochus spurcus, GouLpD; Proceed. Boston Soc. Nat. Hist., 1. 106. 
April 1849. Expedition Shells, 58. 
SHELL small, solid, globose-conic, everywhere sculptured with fine, 
shallow, revolving, alternate grooves and elevations; shining, of a 
dingy yellowish colour, delicately variegated with oblique, zigzag, 
dusky lines, the two colours in about equal proportions, a series of 
somewhat conspicuous quadrate, dusky and yellow spots just below 
the suture; whorls four or five, ventricose, suture deeply impressed, 
the last subangular at periphery; base moderately conical, imperfo- 
rate or minutely umbilicated ; “aperture very oblique, circular; colu- 
mella rounded, arcuate; lip sharp, smooth within, and sub-nacreous. 
Diameter three-eighths of an inch; axis three-tenths of an inch. 
Inhabits the Madeira Islands. Couthouy. 
Has most of the characters of 7. Fermonz, but is very much smaller ; 
it wants the peculiar channeled shoulder of the whorls, and the 
widely open umbilicus. 
Figures 219, 219a@, 2194, three views of the shell, enlarged; 219, 
natural size. 
