The genera of the order macula are, ephelis (freckles); naevus (marks supposed to be the effects of the mother's longing); and spilus (a mole).

The genera of the Squamae are, the lepra (the true leprosy of the Greeks); psoriasis (the scaly tetter); pityriasis (the dandriff); and icthyosia (the fish skin). These are, perhaps, only forms of the true lepra.

The tubercula are, verruca (a wart); moluscum (the small soft wen); vitiligo (soft smooth tubercles); acne (stone pock, the red tuberculated face); lupus (noli me tangere); phyma (boils or carbuncles); frambaesia (yaws); elephantiasis (Arabian leprosy).

We shall add what we consider an improved arrangement of these diseases; but should we err in thinking it such, it will detain the reader for a short time only.

A. Febrile cutaneous diseases. 1.. Papulae. Gen. Prurigo lichen strophulus.

2. Exanthemata. Rubeola, scarlatina, roseola, Purpura, Erythema, Iris.

3. Vesiculae. Varicella, miliaria, erysipelas, herpes, eczema, aphtha. 4.Pustulae. Scabies, impetigo, ecthyma, porrigo, Variola, Frambaesia.

5. Bullae. Urticaria, pemphigus, pompholyx. B. Not febrile.

1. Maculae. Gen. Ephehs, naevus, spilus.

2. Squamae. Lepra, psoriasis, pityriasis, icthyosis.

3. Tubercula. Verruca, moluscum, vitiligo, acne, lupus, phyma, elephantiasis. Cutaneous diseases of the febrile kind often depend on the discharge of some morbid, often a specific, cause; the slight cutaneous affections occasionally appear to be only irritation-communicated from the stomach. In some instances the white of an egg, in others, fish poison almost immediately after being swallowed, certainly long before it can have entered the mass of blood will produce papulae. A proof of its not being owing to any deprivation of the animal fluids is, the eruptions being removed on evacuating the stomach. When owing to poison in the blood, and fever is excited in consequence, the copiousness and violence of the eruption are greatly mitigated by the regulation of the febrile state. If the fluids are forcibly propelled, and carried to the exhalants, so as to pass off in the form of sweat, either from the fluid form or the rapidity of the secretion, a portion is stopped by the cuticle, and inflammation is the consequence. We can easily con-ceive, as in the case of miliaria, where no poison probably exists, that copious sweating in the irritable state of the arterial system, which occurs in puerperal cases, may occasion eruptions; and we consequently find that, by a duly regulated temperature,, this inconvenience can be avoided. In small pox, where a specific poison really exists, the eruption can be always mitigated or even occasionally prevented, by similar measures, viz. remedies peculiarly adapted to lessen the fever. In these cases, the exhalants, which open under the cuticle, convey the fluids in no greater quantity than the pores of this inorganic membrane allow to pass; so that, though the acrimony is occasionally perceptible by a little prurigo, or by the smell, no pustules inflame or suppurate.

It was not without design that we mentioned the form of the fluid discharged; for in almost every instance, gentle perspiration appears better adapted to preserve health and remove diseases than sweating. The form of gas may be chemically more suitable to the morbid cause, than that of a fluid; and it is certainly better adapted to transude through the cuticle, both from its attenuation, and the gentleness with which it is conveyed. Though we have pointed out, in general, the surface as the channel by which the cause is evacuated, yet there is a peculiarity in the order exanthemata, and in one genus of the vesiculae, if indeed it be admitted, we mean the aphtha, viz. that the matter is carried to other membranes: in the two first genera, for instance, to the Schneiderian membrane and the throat; and, in the last, to the membranes of the brain; for erythema differs only from erysipelas in form. The small pox virus is sometimes poured on the tunica conjunctiva, sometimes on the throat, and the villous coat of the intestinal canal; but this is not its usual or natural outlet.

The pustulae we have allowed not to be always febrile; yet they are often so, though the ecthyma -and variola are obviously diseases of this kind: and the former includes the phlegmous. The scabies, though not febrile, has this peculiarity, that it is excited to action by warmth and a more generous diet; but the operation of these existing causes we cannot now examine, until the cause itself is more clearly understood. The existence of an animalcule, producing the diseases, has been lately denied. When, however, the itch has been repelled rather than cured, its form, on its return, is very generally pustular.

The kind of fever in these cutaneous diseases greatly differs. It is inflammatory or putrid, continued or remittent. In the bullae it is generally remittent. For this variety no adequate reason can be assigned: but the continued form of fever is generally observable in those eruptions where the poison is of a specific kind; the remittent form seems rather suited to the sporadic or accidental eruptions.

Several diseases concur in their general nature with the cutaneous. The nearest is dysentery, which greatly resembles them in their pathology and cure. Epidemic diarrhoeas from cold are not very different. Ulcerated throat, pertussis, and croop, are affections of the epithe-lion continued from the skin. But of these we must not now treat.

The cutaneous diseases not febrile arc of two kinds, viz. affections of the cuticle, or of the parts beneath. The maculae and squamae are of the former kind; but the genera included under the first of these are not, as we have said, diseases. Mere pressure on the cuticle will produce squamae, but the causes in general are different. They seem to arise from an acrimony often constitutional, which, however, has not always sufficient power to excite inflammation; or, more probably, they are the diseases of torpid habits little susceptible of inflammatory excitement. This acrimony, either natural or acquired, is gradually deposited under the cuticle till it rises in irregular masses, or, from the pressure beneath, assumes a scaly form. The porrigo might, perhaps, with propriety be referred to this order, except that, as a disease of the roots of the hair, its source is below the cutis. The tubercles, we have said, are seated below the skin. The verrucae are connected with the extremities of the nerves; but their origin is doubtful, and their cure uncertain. The other tuberculae are enlargements of the sebaceous glands as the wens; depositions become morbid by stagnation, as the phymata; or effects of depraved fluids or broken constitutions, as the lupus and elephantiasis; to which the Italian disease, the pelagra, may be added. The tubercles of the elephantiasis are often most horrible in their appearance; and Sauvages has exhausted the monstra hor-rencla informia ingentia in the description. They occur, however, only in the decline of life, and are preceded by marks of a decayed constitution, or depraved fluids. The same appearances also precede the true lepra; but these considerations we must resume under their proper heads; q. v.

It will appear singular that we have referred fram-baesia to the pustulae.. The disease is little known; and the best account of it, that of Dr. Adams, in the 6th volume of the Memoirs of the Medical Society, justifies the change.