GASTEROPODA. 173 
Figure 202, animal, with the shell, as in motion; 202 a, disk of the 
foot ; 202 4, front view of the shell. 
Turso sirius (Gould). 
Testa parva, wmperforata, pyramidata, dilute beryllina, leviter corru- 
gua: spira anfractibus quatuor conicis, infra oblique plicatis, ad 
pertpheriam acutis et spinis compressis ad octodecim armatis: basis 
- planulata, stellaris, iris concentricts muricatis ad quinque insculptis ; 
regione columellari arcuata, levigata ; labro perobliquo. 
Turbo sirius, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 90. 
March 1849. Expedition Shells, 55. 
SHELL small, low pyramidal, of a pale emerald-green colour when 
cleansed, of about four conical whorls, acutely compressed at their 
bases, having about ten oblique ridges on the lower half of the whorl, 
each of which is produced into a delicate, triangular tooth beyond the 
periphery ; and these dentations, with an intervening one of equal size, 
making in all about eighteen teeth, give the base a serrated outline, 
extending up all the whorls ; the surface is moreover faintly corrugated 
by still more oblique folds; base nearly flat, imperforate (the columellar 
region smooth, rounded, arcuate), having about five delicate and dis- 
tantly muricated, unequal rib-strie ; aperture circular ; lip horizontal at 
base, forming a very acute angle with the ascending portion, which is 
very oblique. 
Opercle stony, smooth internally, covered with a gamboge epider- 
mis; sutural region raised ; outer surface finely crenulate at margin ; 
surface of boss slightly indented. 
Diameter half an inch; axis three-tenths of an inch. 
Inhabits New Holland. 
The multitude and regularity of the triangular projections of the 
periphery, when viewed from below, give the base a beautiful star- 
like form, much like T" stedlaris. 
44 
