MITRIDA. 169 
is rarely exserted when they are crawling and lively, but as they 
become languid after capture it becomes distended with water 
and protrudes considerably. When irritated, some species of 
Mitra emit a purple fluid having a nauseous odor. 
The Philippine Islands would seem to harbor the greatest 
number of these elegant and beautiful shells, although a great 
many species were obtained by Mr. Cuming in tropical America. 
They appear to be chiefly confined to the equatorial regions, 
scarcely any being natives of cold climates. The transversely 
ribbed species are frequently found in very deep water, and many 
have been dredged in twenty and thirty fathoms at the Sooloos 
and in the China Sea. 
The Mitride inhabit various stations; many being strictly 
reef shells, where they lurk in holes and crevices under sea- 
weed, but are most generally concealed under stones and blocks 
of dead coral. Others burrow in sand or sandy mud at various 
depths ; some delight in stony ground inside the reefs, where 
they remain concealed under clumps of coral during the day, and 
like the sand species are nocturnal in their habits. 
Although M. Quoy has rightly termed the Mitra an “ animal 
apathique,” the small longitudinally ribbed species crawl about 
pretty briskly over the smooth sand among the low coral islands. 
The Mitra episcopalis (lv, 36), probably on account of the small 
size of its locomotive disk, and the ponderous nature of its 
long shell, is, however, a very sluggish mollusk. Some of the 
Auricula-shaped Mitres that live among the Philippines, in the 
shallow pools left by the receding tide, crawl about the stones 
out of the water, in company with Planaxis and Quoyia. The 
Mitres, like many of the large Volutes, prefer, however, to asso- 
ciate together, and may be seen in dozens crawling over the 
sandy mud-flats in shallow water, being most active just as the 
flood-tide makes. When the tide recedes, they bury themselves 
superficially in the yielding soil, and are with difficulty dis- 
covered. Some of the small ribbed species cover themselves 
entirely with the sandy mud, and in that disguised condition 
travel about with comparative security. 
MITRA (typical). Mitriform, thick, spire elevated, apex sharp; 
mouth rather small and narrow, notched in front; columella 
obliquely plicate ; lip rather thick, smooth within. 
[voLuToMITRA, Gray. Separated from Mitra on account of 
the peculiar dentition of an Arctic species, V. Grenlandica. 
Twenty additional species have been included in the group by 
H. and A. Adams; they are all Mitras in appearance, and the 
dentition of none has been examined, except that of V. cornea, 
which decidedly differs from V. Granlandica, and is of the 
regular Mitra type. | 
AIDONE, H. and A. Adams. Shell fusiform, smooth, polished, 
12 
