278 Mr. Children's Abstract of the Characters of 



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 de- 

 posited upon them, but are precipitated in the air itself, af- 

 fecting 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. 8? E. 

 KL.S. $c* 

 TN SamouehVs Entomologist's Useful Companion, as well 

 * as in several other works of deserved reputation, the names 

 of the Genera established by Ochsenheimer, in his Schmet- 

 terlinge 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 re- 

 spective 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 Ochsen- 

 heimer'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 im- 

 proved sketch of his arrangementof the Europaean 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 



