314

REPORT ON ZOOLOGY, MDCCCXLIV.

from the proper segments, though in reality a modification of these. Thesegments have that designation -when they can he drawn in or pushed forthat will. The Reporter does not think this mark precise enough to distin-guish the one from the other in every case ; instances often occur where eitherdenomination might he applied with equal justice. The spiracles afford thesurest mark, as has been already stated. (Report, 1843, p. 122.) Neither canhe agree with the views of the author respecting the first segment. In theMonograph of the Staphylinidae it is laid down that the first dorsal segmenthas none corresponding to it on the underside, but Schiodte asserts thatevery dorsal has its corresponding ventral segment. Anatomically, it istrue, a ventral segment may be demonstrated, opposite to the half ring theretreated as the first of the back, but it is of no consequence as a segment,and the one which comes after is articulated directly with the breast.Subsequently the Reporter has become convinced by the comparativeexamination of different families, as well as of the earlier states, that thissegment is properly the second, and that the first (likewise without a con-tinuation on the underside) lies still more forwards, and is in fact the partcommonly regarded as the postscutellum of the metathorax, to which thelarge spiracles belong, treated by all authors, and also in the work lastcited, as the spiracles of the metathorax. Although more resembling in sizeand form the spiracles of the thorax, than those of the other abdominalsegments, the consideration of the metamorphosis proves that they areidentical with the pair placed in the first segment of the abdomen in thelarva* Accordingly the Coleoptera in general possess two dorsal segments

* This later view of the learned and philosophical editor of the Archives remains, however, open to discussion. It seems, for instance, fully asreasonable, from the more separated and contrasted forms of the severalparts in the perfect insect, to proceed and identify their counterparts in thelarva, where the distinction of thorax and abdomen is usually less marked,as it is to assume first the line of division (arbitrary by comparison) in thelatter, and thence to impose upon the former denominations at variance, itmay be, with the position and apparent office of the parts which they arehere employed to denote. If in some insects in the perfect state (asOrthoptera ) it may seem allowable to assign the segment in question as wellto the abdomen as the thorax, yet in the gx-eater number, but particularly inthe small-waisted Hyxnenoptera, its intimate connexion with the thorax isevident, and no describer has ever been at fault in regard to it. ToNewmanthe merit belongs of having pointedly called attention to the mutualrelation and eharacteristic importance of this and the following segment, towhich he gave respectively the names of propodeon and podeon; termswhich might stand, unless considerations of harmony in the description ofthe thorax should recommend for the former a name framed in accordance