If cutaneous diseases have been imperfectly, and with too little discrimination, described or considered by the practical physician, they have claimed a large share of the attention of nosologists, in whose systems each blemish on the skin has been magnified into a genus of disease. We cannot help smiling when to the last of the Linnaean genera in his nosology, which is only a. freckle, the following pathetic exclamation is added:

Hei mihi! tot mortes homini quot membra, malisque Totsumus infecti, mors ut medicina putetur.

In one view, the attention of nosologists to these diseases was properly employed, and, above all, the luminous terseness of the Linnaean language, viz. for the purpose of distinction; yet, were criticism our object, we could show that both Linnaeus and Sauvages have failed in attaining this end; nor was accurate discrimination to be probably obtained without coloured plates, resembling those of Dr. Willan. Former authors gave little assistance: Mercurialis was too concise and imperfect; Plenck often obscure and inconsistent; Lorry,in his quarto volume, superficial and indistinct: and the ancients imperfect, confused, and inaccurate in their descriptions. In fact, previous to the appearance of Dr. Willan's work, our best assistant was Sauvages, in his larger work on nosology.

As we, in general, approve of Dr. Willan's arrangement, we shall first explain it, with his own remarks, so far as he has proceeded, adding those in the orders which have not appeared, that their arrangement suggests; after which we shall subjoin what appears to us an improved order, and an outline of the pathology of those complaints: the latter attempt,we believe,is new, and therefore, we trust, its imperfections will be excused.

Dr. Willan's orders are natural ones, viz. pimples, scales, rashes, vesicles, pustules, tubercles, and spots. The arrangementof these orders is of little importance; yet it has been suggested that it would have been more correct to have placed those first in which the protuberance was inconsiderable, and to have proceeded according to their increasing magnitude, as spots, rashes, pimples, scales, vesicles, pustules, and tubercles. Perhaps it would be still better, keeping this idea at the same time in view, to divide them into febrile and not febrile; including in the first class, pimples, pustules, vesicles, and rashes, and the others in the second. As the genera are introduced by Dr. Willan, this arrangement is not perfectly correct; but we shall employ it as more suitable to our pathological enquiries.

The pimples are styled papulae: they are small elevations of the skin, with an inflamed basis rising to a point, with either no, or a very imperceptible, fluid. When any fluid is present, it is serosity, sometimes peculiarly acrid, and never becomes purulent, but occasionally desquamating in branny scales. The genera included by Dr. Willan in this order are, the strophulus (the red gum, a vulgar corruption of the red gown, from the generally diffused colour); the lichen (the eruption in the spring, or from heat); and the prurigo, or the pimples which arise with general itching. The term pimples, or the equivalent appellation in different languages, has been employed with little accuracy. In our author's definition they are properly and strictly limited; perhaps too strictly. The prurigo he has not, we think, properly defined. It is an itching of the skin, with small papulae, seldom discoloured, with very slight fever, and without contagion. All these genera are connected with a febrile state of the constitution.

In the pustules which follow, the little inaccuracy of which our arrangement is liable appears more conspicuous. Few are febrile diseases; but the itch, in its appearance, connects this order with the pimples, and the introduction of variola reduces it to the febrile complaints: nor, indeed, is the tinea wholly free from the suspicion of being originally a febrile indisposition.

The genera are, scabies (itch); impetigo (a running scab); ecthyma (an ulcerated tetter); porrigo (scald head); and -variola (smallpox). The itch, certainly, at times degenerates into the impetigo; and sometimes, in a secondary chronic state, forms distinct pustules.

The vesiculae contain the following genera, viz. the varicella; the pemphigus; the pompholyx; miliaria; erysipelas; herpes (shingles); eczema (heat eruption); and aphtha (thrush). There may be some doubt of the propriety of admitting aphtha as an affection of the epithe-hon, though it be a continuation of the skin. In that case, syphilis, cynanche maligna, and mercurial sores, should have a place as cutaneous diseases. In this order the genera are arranged according to the magnitude of the vesicle, except in the case of the varicella, to connect this with the former order. Each, except perhaps the eczema, is preceded by fever, as we shall show under the different heads. In the last fasciculus, we perceive that Dr. Willan has made some alteration in his arrangement, by including the erysipelas, the pemphigus, and the pompholyx,in a separate order, which he styles Bullae; but it is unnecessary to notice it particularly, as it does not materially alter our present views.

The hashes, exanthemata, contain the Urticaria (nettle rash); rubeola (measles); scarlatina (scarlet. fever); roseola (rose rash); purpura (scorbutic rash); erythema (red rash); and the iris (the rainbow rash). This, with the exception of the urticaria, whose vesicles sometimes rise above the skin, and might, perhaps, be with propriety arranged in our author's new order, bullae, form a truly natural association.

The cutaneous diseases not attended with fever, are the maculae (spots); Squamae (scales); and tu-bercula (tubercles). The first contains those little insignificant deviations which do not constitute diseases; the second are disgusting and obstinate complaints; and the tubercles are often the most frightful masses.