known, may probably amount to near thirty.

The flight of these Swallow-tailed Hesperidæ, is usually performed in the morning and evening, and is so rapid, as frequently to elude the eye of the observer. They rest with all the four wings perpendicular, similar to the Swallow-tailed Butterflies, (P. Machaon, &c.) The present is a very rare species; we captured only two specimens near Bahia.

EUDAMUS Doryssus.

The sexes of this species materially differ. Our figure represents the female: in the male, the wings are browner, and highly glossed at their base with green; the snowy border on the posterior wings is very narrow above, but much broader beneath. It appears very locally distributed; we found it common in the vicinity of Bahia.

MITRANÆ Pl. 4.
Mitra episcopalis.

MITRA Episcopalis.

Family Volutidæ.—Sub-Family Mitrianæ.

Generic Character.

Specific Character.

We view this elegant, though common shell, as the type of the Lamarkean Mitres, a group we shall hereafter consider as a sub-family. It is common in various parts of the Asiatic Ocean, and sometimes occurs of gigantic size: in its natural state it is covered with a thin olive epidermis.

We regret that the nature of this work will not permit us to do more than furnish the clue, to the natural arrangement of the two typical groups of this family, Voluta and Mitra. The first of these we have, indeed, pledged ourselves to enter upon more fully in Exotic Conchology. But the arrangement of the Volutes is so intimately connected with that of the Mitres, that we scarcely know how to illustrate one, without perpetually adverting to the other.

The two typical groups of the Lamarkian Mitræ we now characterise from their shells; they correspond to those of the typical Volutes; while their internal relations may be learned from the respective types of form here designated. The genera Mitra and Tiara, each present a circular series of affinities, and are united by the fourth type in each group. Even a partial study of this disposition will reveal to the Conchologist a harmony of design, amid the greatest diversity of structure, which he could scarcely have suspected in the mere covering of an animal.

The shells which appear associated with M. episcopalis, in this type of form, are never coronated: the only external sculpture which they in general possess, are delicate rows of minute punctured dots, in the typical examples, as Pertusa, millipora, versicolor, the outer lip is acutely toothed; while in the aberrant species, Melaniana, tessellata, scutulata, &c. this part is smooth.

MITRANÆ Pl. 5.
1. Tiara isabella. 2. sulcata.

TIARA isabella.

Fawn coloured Mitre.

Order Zoophaga. Family Volutidæ.

Sub-Family Mitrianæ. (G. Mitra. Auct.)

Generic Character.

Specific Character.

It is highly probable that the Mitres, like some other carnivorous marine animals, seek their prey, and habitually reside, in the deep recesses of the ocean. Instances are recorded of individuals having been brought up from great depths; and notwithstanding the number of species, of which we already know near 150, very few are common.

This genus, in short, is now become too overloaded, even for the purposes of artificial arrangement: but we refrained from characterizing any other group than Conohelix, until we analized the remainder. Tiara appears to be the second, or sub-typical group. The subordinate section, or type of form, represented by T. isabella, includes several little known shells, all marked by delicate transverse ribs and longitudinal striæ: the outer lip is not strictly toothed or crenated, but is merely undulated by the external sculpture: this subordinate group in Tiara, is aberrant: all the species whose habitat we know, have come from the Pacific Ocean.

Tiara isabella is a shell of the greatest rarity. Our drawing was made from a specimen (presumed unique) sold at the Bligh Sale for 3l. 3s. It was stated