504 Miscellaneous. 



affecting the earth's surface, and their results, — the rocks and strata 

 formerly produced and subsequently altered, or worn away and re- 

 produced, by similar agencies, — the meaning of fossils, — the succes- 

 sive groups of strata, or " formations," and their chief characters, — 

 and, altogether, the history of the earth, deduced from the facts 

 observable in it. as interpreted by the processes now in operation — 

 these arc the divisions of the subject-matter of this well written and 

 conscientiously edited little book. Some of the latest information 

 bearing on minerals, lithology, the Cambrian and Cretaceous systems, 

 and the Glacial period have been concisely and carefully incorporated 

 in this edition. 



MISCELLANEOUS. 



Anatomical and Morpliological Researches on the Nervous System of 

 Hymenopterous Insects. By M. Ed. Bkandt. 



The nervous system of the adult Hymenopterous insects is little 

 known, still less that of their larvae. There does not exist any 

 investigation of the metamorphoses which the ganglionic chain 

 undergoes in the passage from the larval state to that of the adult 

 insect. 



The nervous system of only eight species of Hymenoptera is 

 known; these are Bomhus mnscorum, Apis mellijica, Vespa crahro, 

 Scolia hortorum, Formica Ucpiipercla, Ichneumon atropos, AthaUa 

 centifoJice, and Sirex gigas. 



Comparative and morphological researches are wanting. I have 

 undertaken with this view a study of the nervous system of the 

 HjTuenoptera, by dissecting a number of species of the same group. 

 I have thus determined the morphological character of the neiTOUs 

 system of each family. Having tenninated my researches on the 

 Hymenoptera, I have the honour of submitting to the Academy 

 their principal results. 



I have studied the nervous system of the adults in seventy-eight 

 species belonging to all the families of Hymenoptera and to most of 

 the genera, that of the larvae in twenty-two species, and the meta- 

 morphoses of the chain of ganglia in fifteen species. 



I. The Nervous Systein of the Adult Hymenoptera. — There are 

 two cephalic ganglia (a supraoesophageal and a suboesophageal 

 ganglion), two or three thoracic and from three to seven abdominal 

 ganglia. The Apides and the Wasps ( Vespa, Odynerus, Eumenes), 

 as well as the Crahrones i^Ectennius and Thyreopus) and Chrysis 

 have two thoracic ganglia, while Cerceris, Ammophila, Pompilus, 

 Formica, Mutilla, Myrmosa, the Entomospheces and the Phyto- 

 spheces (Cimbex, Tenfhredo, Sirex) have three thoracic ganglia. In 

 the Hymenopterous insects with two thoracic ganglia the second 

 always presents, in its middle, a more or less distinct emargination, 

 an indication of the fusion of two ganglia. Sometimes the inden- 

 tation is verj- marked and the ganglion becomes double (Odynerus). 



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