which, I believe, develops its existence in the air: whereas, if these are cut down and the ground cleared, a good radiating surface becomes immediately exposed, and the dissipation of caloric with its accompanying effects directly ensues.-" A portion of grass-plat," says Mr. Daniell in his Meteorological Essays, "under the protection of a tree or hedge will generally be found on a clear night to be eight or ten degrees warmer than surrounding unsheltered parts; and it is well known to gardeners that less dew and frost are to be found in such situations than in those which are freely exposed."-Dr. Macculloch in noticing the comparative healthiness of ancient and modern Rome, thought it not unimportant to notice what Theophrastus has stated with regard to the plain of Latium, which this historian says was covered with laurel and myrtletrees of such a size as to be used in ship-building; and this remark, if terrestrial radiation has any thing to do with the development of malaria, is not so fanciful as one of his reviewers seems to imagine it*. Again, If terrestrial radiation is the cause of the deleterious influence of those effluvia existing in the atmosphere, we are no longer surprised at finding rice-grounds, which are kept in a constant state of wet or moisture during the growth of the plants, prolific in the diseases which malaria occasions. "Dr. Macculloch is convinced that the minute marshy or swampy spots which occur in thousands of low situations, whether on commons, near woods by road sides, or in innumerable other places where they hardly ever attract notice,→ are productive of malaria ; though their limited range of action generally renders their power insensible, unless when houses happen to be erected in their vicinity."-" In how far meadows which cannot be called marshy are capable of producing malaria, is an intricate and entangled question. It appears certain, however, that there are many tracts of meadow or of alluvial land not marshy, and often not intersected by ditches, at least in a conspicuous manner, which are the sources of malaria all over Europe." Essay, p. 69.-" Such is the case with all the alluvial tracts at the entrances and sometimes at the exits of the lakes of Switzerland and elsewhere; and in places innumerable where there is no proper marsh, nor even an approach to such a character, but where the prevalent diseases must be owing to malaria."-" Volney, while travelling in America, has averred that every valley in the country which he visited produced the fevers of malaria, enumerating among the sources of this poison not only marshes and wood, but * Medico-Chirurgical Review, January 1828. rivers, rivers, millponds, &c."" The meadow lands about Fontainbleau, at the junction of the Yonne and the Seine, are notorious for the fièvre du pays; so injurious are they, that few escape intermittents or remittents over a considerable tract." If some great portions of the meadow-land in England have been recovered by drainage from a state of marsh, and are now as dry as the ordinary low-lands of plains and valleys; and if these localities still produce malaria and its consequences, it is another point of evidence against the salubrity of meadows generally." It is a rooted opinion in England, that there can be no malaria on the banks of a running stream; and as far as mountain-torrents are concerned, this is probably true: but where rivers slowly meander through low grounds, we must not trust to the mere motion of the water.". "For whatever persons may still think as to rivers in general in our own country, there is no doubt that such streams as the Ouse, the Lee, and all others flowing with difficulty through fertile meadows, and with a flat vegetable margin, are productive of malaria." But not to occupy more than necessary the time of the reader by quoting further from Dr. Macculloch's Essay, I shall only observe that this author has found small streams bordered by thin and grassy margins; tranquil and stagnant waters, especially in hot countries; and ponds occupying but a small space, to be productive of evening mists,' the results of which are autumnal and intermittent fevers." And is not the terrestrial radiation of caloric, I would here ask, the cause of those evening mists which favour the attacks of these disorders? Indeed it is remarkable to find that every locality pointed out by the Doctor as productive of malaria, will be found to possess one or other of those circumstances which promote the dissipation of heat from the ground. It has long been known that water and a grassy surface are excellent radiators of caloric; and the effects of this process-fogs, damps and dew-were ob served long before the cause of them was properly understood. "A valley," says Mr. Daniell*, "is more liable to the effects of radiation, than the tops or sides of hills; and it is a wellknown fact that dew and hoar-frost are always more abundant in the former than in the latter situations. The influence of high hills is, however, often prejudicial to the valleys at their feet; for the condensed and moist air rolls down their sides, and lodges at the bottom: these, therefore, are protected from the chill, while a double portion falls upon what many are apt to consider the more sheltered situation. It is a very old remark, that the injurious effects of cold occur chiefly in hollow places, and that * Meteorological Essays and Observations. frosts frosts are less severe upon hills than upon the neighbouring plains: and it is consistent with my own observations, that the leaves of the vine, the walnut-tree, and the succulent shoots of Dahlias and potatoes, are often destroyed by frosts in the shel-. tered valleys, on nights when they are perfectly untouched upon the surrounding eminences." The diminution of temperature which is produced upon the surface of radiating bodies during the night is communicated by slow degrees to the surrounding atmosphere; and if the process goes on for any considerable period, moisture and probably other matters are not only deposited upon them, but are precipitated in the air itself, affecting more or less the feelings of every one within its range, but particularly the weak or unhealthy. [To be continued.] XLIX. An Abstract of the Characters of Ochsenheimer's Genera of the Lepidoptera of Europe; with a List of the Species of each Genus, and Reference to one or more of their respective Icones. By J. G. CHILDREN, F.R.S. L. & E. F.L.S. &c.* IN N Samouelle's Entomologist's Useful Companion, as well as in several other works of deserved reputation, the names of the Genera established by Ochsenheimer, in his Schmetterlinge von Europa, are frequently quoted, but the characters on which they are founded wholly omitted, so that they can only be inferred from a laborious comparison of those of their respective types, a task few persons will be disposed to submit to, in order to clear up an occasional doubt, as to what genus such or such an insect is to be referred. This inconvenience is attributable to the want of an English edition of Ochsenheimer's work; and in some measure to lessen it, the following translation of his Family and Generic Characters is offered to the British student. Ochsenheimer died in 1822, leaving his work incomplete, only four volumes having been published in his life-time, the last of which appeared in 1816, and consists chiefly of an improved sketch of his arrangement of the European Lepidoptera from the first genus to the eighty-seventh. Before his death, however, only the first forty-three genera were published in detail, with the characters and descriptions of their respective species; these occupy the first three volumes, the last of which terminates with the genus Eyprepia; for the fourth contains, besides the sketch of the arrangement, only notes concerning * Communicated by the Author. some some of the species published in the former volumes. The. work is continued by M. Frederick Treitschke, and the specific descriptions are completed to the hundred-and-sixth genus inclusive; and M. Treitschke has also given a further sketch of the arrangement, including ten additional genera consisting of the Phalana Pyralides of Linnæus, the specific descriptions of which are not yet published*. More therefore still remains to be done, and we wait anxiously for the completion of the work. In the mean time we lay the present abstract before the reader; and should he entertain any doubts of the value of M.M. Ochsenheimer's and Treitschke's labours, we refer him to the Introduction to Dr. Horsfield's Descriptive Catalogue of the Lepidopterous Insects contained in the Museum of the East India Company, where he will find such ample testimony to their merit as cannot fail (unless he disregard the maxim “ laudari à laudato,") presently and effectually to remove them. 1st Division.-PAPILIONES. Wings when at rest, erect. Antennæ filiform, generally capitate, or terminated by a knob; sometimes only slightly incrassate at the end. Flight, diurnal. Larva with sixteen legs; head globular, perfectly distinct from the body; motion indolent, and sluggish. Pupa angular. Metamorphosis generally naked, or not concealed by a web. Genus 1. MELITEA, Fab. MELITEA, Fab. Syst. Glossat. BATTUS et GRAPHIUM, Scopoli. Introductio ad Hist. Nat. Legs, first pair imperfect. Wings, roundish; upper surface of the anterior wings, reddish-yellow with black maculæ and dots, or blackish, with reddish-yellow macula and dots; under surface of the posterior wings with alternate orange-yellow, and yellowish-white cross bands with black spots; not silvered. Antenna, knob oval, compressed, obtuse. * The last volume as yet published is the sixth, of which, Parts I. and II. appeared in the present year. Larva with seven or nine conical, fleshy protuberances, covered with short hairs, on each of the middle segments of the body, and two larger on the side of the throat. Pupa, anteriorly rather obtuse, hinder part usually with elevated points; not suspended in any constant manner. Icon. Ernst, I. Pl. XVII. f. 27. a. b. Ernst, I. Pl. LXI. Suppl. VII. Ernst, I. Pl. LXII. Suppl. VIII, Ernst, I. Pl. XIX. f. 31. c. d. Genus 2. ARGYNNIS, Fab. ARGYNNIS, Fab. ARGYREUS, Scop. Legs, four perfect, gressorial. Wings subdentate, upper surface generally reddish-brown with black spots; under surface with silvery bands or spots. Antennæ capitate, knob compressed. Larva with six longitudinal rows of ramose spines, and two others, generally larger than the rest on the first segment; a broad, longitudinal, dorsal band, divided by a medial line. Pupa, suspended variously; cavity of the neck, and the neck, with brilliant points. Species. Icon. Hübn. Pap. Tab. 5. f. 23. 24. Ernst, I. Pl. XVI. f. 23. a. b. 5. A. Pales, |