452 NATURAL HISTORY OF HAWAII. 



describe the various species accurately, in a way to be of use in identifying the 

 beach-worn specimens, is obviously a task beyond the scope of this volume. 



Margin Shells. 



The margin shell ^"^ family includes small shells related to the cowries and 

 mitres. They are pear-shaped, porcelanous in appearance, and are marked by 

 the large body whorl. The aperture is usually nearly the whole length of the 

 shell, and the outer lip has a narrow thickened margin which may be toothed 

 or smooth witliiu, but the columella is distinctly jilicated nuich as in the mitre 

 family. 



Since the largest of the four species of margin shells so far collected in 

 Hawaii is less than a fourth of an inch in length, they are liable to be secured 

 only by those accustomed td close observation. The largest species"'" is 

 smooth, pale rosy-white, with two brownish bands, and has the outer lip 

 slightly thickened in the middle. It is the only species belonging to the genus 

 taken here, but is, of course, too small for satisfactory photographic illustra- 

 tion. The typical genus of margin shells"* embraces perhaps two hundred and 

 fifty species. Of this number a dozen or more are Polynesian, three being 

 credited to this group, two of which have been taken on Oahu. They have 

 the outer lip conspicuously thickened, with the inner margin smooth, ridged 

 or toothed in different species. 



Olive Shells, 



Tlie olive shells arc rare in Hawaii. The family '''* is so far represented 

 by four species, none of which seem to be common. Only the beautiful conoid 

 harp-shell *•* is commonly collected. This species, which shares the Hawaiian 

 name pu with the triton shell, belongs to an important sub-family "^ in which 

 the species differ from those in the typical sub-family ^- in several important 

 respects, among them being the conspicuous and characteristic longitudinal 

 parallel ribs on the shell. These ribs, together with the general harp-like 

 shape of the shell, amply justify the common name. The color scheme is 

 brown in many shades, and the pattern, resembling the banding of an agate, 

 makes of the harp .shell an object greatly admired. 



The typical olive shells are smooth, solid, highly-colored, and agree with 

 the group just described in having the outer lip simple and the aperture 

 obliciuely notched below. The red-mouthed olive ''^ is a typical species. It 

 has a deep orange-red aperture, and the pale creamy ground is variously 

 banded with chestnut, but the general color scheme varies greatly. The species 

 is said to inhabit muddy sand in deep Avater, where it attains a length of two 

 or three inches. A small species of olive "* less than an inch in length, is white 

 within and without, and is marked with two wide and one nai-row rich orange 

 bands. It is a common wide-ranging species and together Avith a third unde- 

 termined species has been collected by Mr. Thaanum on Hawaii. 



' Marginellida\ ^' Erato 

 ■ narpinm. »- Oiivina;. 



