44 Dr. A. S. Packard, Jr's Revision of the 



vertebrates than in any other articulates, for it is brain force which 

 more immediately decides the rank of animals than any other single 

 character. The most intelligent of all insects, with a greater dif- 

 ferentiation of the individual into sexes, and dimorphic sexes, with the 

 division of labor carried out more minutely than in any other 

 articulates, and in their intimate relation to the wants of man, the 

 hymenoptera, and especially the Hive bee, to our miud, are true syn- 

 thetic beings, as that term was used by the Botanist Fries, standing in 

 the same relation to all the articulate series below, as the apple tree to all 

 other plants, and in a strictly zoological point of view, as man does to all 

 other vertebrates. The bee concentrates in its form all the normal 

 characters of insects, and lacks the degradational features showed in 

 greater or less abundance by those standing below it. 



Some of the most useful characters in the Crabronidae exist in the 

 form of the clypeus, the comparative breadth of the epicranium, or 

 breadth of the front between the eyes; and its sculpturing and amount 

 of pubescence or hirsuties; in the antennae, the relative length and 

 proportion of the joints composing the scape and flagellum • as 

 well as the size and proportion of the entire head, and especially the 

 degree of convergence of the sides behind the eyes. In separating 

 perplexing species we always first look at the sculpturing of the pro- 

 podeum of Newman,* or u thoraco-abdominal ring" of Newport, which, 

 though closely united with the thorax, is in reality the basal ring of the 

 abdomen, which, during the semipupa state, is in the hymenoptera 

 transferred to the thorax, the rings of which it so closely simulates in 

 form, sculpturing and colors, as to have led some of our best observers 

 to confound it with the meta-thorax. It is this single character which 

 separates most trenchantly the hymenoptera, as a group, from all other 

 insects. In the Tenthredinidae the propodeum is much as it exists in 

 the lepidoptera, where it forms a membranous ring, less hard in con- 

 sistence than either the thoracic or abdominal rings lying next to it. 



In the Crabronidas the end of the abdomen presents excellent 

 generic and also specific characters, depending on the grooved or flat- 

 tened tips. This part varies less in the Philanthinae, and is of slight 

 use in most of the Nyssonidaj. 



* The metascutumand metathorax of most authors — See our remarks, on this 

 segment and its developmental history, in Proceedings Bost. Soc. Nat. Hist., 

 Feb. 7, 1866. 



