282 ASTRALIUM. 



transversely oval, very oblique, generall)^ golden Avithiu, and stained 

 with pnrple or blue on the columella. Alt. 28, diam. 40 mill. 

 Indian Ocean ; Australia ; Philippines ; New Caledonia,; Java, etc. 



023erculum oval, nucleus submarginal ; outside deep bluish-green, 

 excavated around the upper margin and near the middle, edges 

 rugose, center nearly smooth. 



Trochus aculeatus Gmel. is a synonym. 



An extremely variable species. In form it may be either conic 

 with nearly flat base, or flat above with very convex and uuibilica- 

 ted base. The spines are generally triangular and oliliquely wrink- 

 led above, but are often square and elaborately foliated at the ex- 

 tremities. Restricting the typical calcar to shells with moderately 

 exserted scalariform spire, depressed a{)ex, and body- whorl deflected 

 toward the aperture, we may define several varieties which are typ- 

 ically quite distinct, but which, in the large series before me, are 

 connected with each other and with the type by insensible grada- 

 tions. 



Var. HELiciNUM Gmel. PI. 52, figs. 28, 31. 



Last whorl not descending ; spire conical, not much depressed at 

 apex ; marginal spines generally short. Usually larger than the- 

 typical form. A specimen before me measures : alt. 40, diam. 70 

 mill. 



Var. LACiNiATUM Gould. PI. 53, figs. 32, 33. 



Shell bullet-shaped in the adult ; aperture subcircular, white 

 within ; columella generally stained with purple. 



Alt. 28, diam. 22 mill. 



Philippines (Gould), Viti Is. 



Young shells are like var. helicinum; the adults are very difl^er- 

 ent in shape, and sometimes even more elongated than in the figure. 



Var. PLANORBis Pilsbry. PI. o6, figs. 75, 76. 



vSpire planulate, scarcely at all exserted ;. base very convex, nra- 

 bilicated. x\.lt. 10, diam. 27 mill. 



A curious form, very different from the preceding. 



A. STELLARE Gmel., 1788. PI. 55, figs. 66-68. 



Shell imperforate, conoid, solid, more or less elevated, whorls 

 5-6, obliquely radiately costate, imbricately spinose at periphery, 

 the last carinated, carina with about ten long vaulted sj)ines ; base 



