108 Historical Sketch of Improvements in [Aug. 



the old genera scarabsBus and lucanus of Linne, into natural 

 families, by W. Mac Leay, Esq. has lately been published, and 

 reflects honour on its author, who has treated the subject with 

 philosophical rigour. His first chapter contains admirable obser- 

 vations on the characters which should be employed to distin- 

 guish the genera and families, with remarks on the abuse of 

 several of them, by which, genera that are nearly allied, have 

 been placed at a distance from each other. He has also shown 

 that generic distinctions have been founded on the supposed 

 want of parts which have in fact existed, although in a very low 

 state of development. Chapter 2 treats of the actual state of 

 our knowledge with regard to the classification of the Linnean 

 scarabeei. In the third, the author discusses the difficult subject 

 of nomenclature. The following chapter contains observations 

 on the affinities which the Linnean scarabsei bear to each other. 

 The fifth contains remarks on the Linnean genera lucanus and 

 hister. The sixth, general remarks on the geographical distri- 

 bution of the petalocera. The seventh and eighth, on the five 

 famihes of petalocera that feed on putrid or decomposed, and the 

 five families that feed on o-reen or living vegetable matter. The 

 last chapter contains concluding remarks ; and the appendix 

 treats of the genera of the rectocera, or of the old genera hister 

 and lucanus; and of the petalocera or scarabseus of Linne. 



We feel extremely sorry that we have not time to give minute 

 details of this admirable work, to which we must, therefore, refer 

 our readers. 



Mr. Kirby has published two papers in the Transactions of the 

 Linnean Society ; the one entitled a " Century of Insects," the 

 other *' Description of several new Insects discovered in New 

 Holland by R. Brown, Esq." in which several new genera and 

 species are described. 



Class V, CllUSTACEA. 



In the Journal of the Academy of Natural Sciences of Phila- 

 delphia, the Crustacea of the United States have been described 

 by T. Say, Esq. in a manner that reflects great credit on this 

 zealous zoologist, who has estabhshed several genera, and disco- 

 vered several new species of recently discovered European 

 genera. 



In the " NouveauDictionnaire des Sciences Naturelles," vols, 

 xii. and xiv. are two papers by Dr. Leach, on the family Cymo- 

 THOAn.E, and on the Entomostraca, in which are established 

 18 new genera. 



In the Annals of Nature, Rafinesque has given three new 

 genera of those Malacostraca, which have sessile eyes. The 

 first two belong to that great division, having their bodies late- 

 rally compressed, both of which are inhabitants of fresh-water, 

 and are named by him Sperchits, and Leplurus. The other 

 genus LiRCEUS is referable to the second grand division of the 

 same great group, whose bodies are depressed from above. 



