RISSOA. 123 



This pretty species of lUssoa varies in shape from oval 

 conic, to seniifusiform, is tolerably strong, or at least not 

 very thin, a little translucent, and with a resinous lustre. 

 It is whitish or yellowish horn colour, and is encircled in 

 the typical examples with hands of rufous brown or intense 

 fulvous; three upon the body and two upon the penult and 

 antepenult volutions. Of the zones upon the final whorl, 

 the middle one, which follows the line of the junction of 

 the outer lip to the body, is the principal ; only a narrow 

 strip of it is perceptible at the lower suture of the smaller 

 turns ; the upper band, which is the more marked one 

 upon the earlier volutions, is usually rather narrower, and 

 lies at some distance from the suture ; the third or ter- 

 minal one encompasses, and often stains the columella, 

 which last is occasionally also tinged with liver- colour. 

 Numerous rounded costellar strise wind round the body 

 whorl, and although apt to become partially obsolete else- 

 where, are always distinctly visible upon the basal area of 

 adult examples ; for the most part, too, obscure and irre- 

 gular wrinkles traverse the shell lengthways. There are 

 about six and a half whorls, whose convexity is so trifling, 

 that the lateral outlines are nearly rectilinear. They are 

 rather short, and are divided by a clearly defined yet 

 simple suture. The body occupies from two-fifths to three- 

 sevenths of the total length, but usually the former propor- 

 tion. The commencement of the basal slope, from its usual 

 flatness, is more or less subangulated. The apex is very 

 small, but blunt. The mouth, which is smooth within, 

 and occupies about two-fifths of the total length, is oval- 

 pyriform, being rounded, though often somewhat narrowly, 

 below, and contracted to a point above. The outer lip 

 is acute, not much arcuated, and not at all projecting. 

 The pillar is shelving, tolerably broad, and elevated at 



