MONOGRAPH OV THE NORTH AMERICAN PROCTOTRYPID^. 11 



dentate or pedicellate and verticillate. In some groups tlio number of 

 joints is alike in both sexes, but in others they are more numerous in 

 the males, while in at least one group, the Belytiiiai, the females have 

 the greater number. 



The mandibles are in the majority of the groups bidentate or bifid, 

 but in the Beth ylina? and Dryininai they vary from 2- to O-dentate: 

 Apencsia has but 2; Epyrin and Mesitius 5 or G; Scleroderma 3 ov 4,, 

 etc. Most of the genera in the Dryininai have 3 or 4; the Scelioninai 

 2 or 3; while in only one group, the Proctotryjnnae, are tliey eden- 

 tate. The maxilhie, PI. i, Fig. 2, terminate in (me or two large, thin, mem- 

 branous lobes, the galea and lacinia, while the mentumis small, horny, 

 or coriaceous. The maxillary palpi vary in the number of joints from 

 2 to and are usually conspicuous from beneath. The labial palpi, PI. 

 I, Fig. 3, on the contrary, are short and inconspicuous, usually 2- or 3- 

 jointed, the terminal joint being the longest; while in one group, the 

 Platygasterina?, they are 1-jointed. 



THK THORAX. 



The thorax is, as a rule, rarely very much narrower than the head, 

 variable in breadth and length in the different groups, and is of the 

 greatest importance in classification. The three princi^ial divisions are 

 the pro-, meso-, and meta-thorax, and as it is essential that the compo- 

 nent parts of each of these divisions should be thoroughly understood, 

 they are here taken up separately, the parts being explained by letters 

 on PI. I, (Fig. 1, T.) 



The prothorax '(Fig. ^^) is large and conspicuous from above, with 

 but few exceptions, in the Bethylinic, Emboleminje, Dryinina', Procto- 

 trypina?, and in some of the Scelioniiiiie, while in the other groups it is 

 more variable, usually short and inconspicuous, sometimes very small, 

 and often not, or scarcely, visible from above {Tele)wmi(s, etc.). It sup- 

 ports the head and front legs, and its principal component jiarts are: 

 (Fig. pn) the pronotum, (Fig. x>) i^^^ pleuron, and (Fig. sp) the praester- 

 num. 



Tlie mesothorax is the largest division of the thorax. It supports 

 the front wings and tlie middle legs, and variations and peculiarities 

 noticeable in its various sclerites have been found to be of excellent 

 specific and generic value. The principal sclerites are: (Fig. 7ns) me- 

 soscutum, which is frequently subdivided into three parts by longitu- 

 dinal furrows (Fig. |)/) called the parapsidal furrows; it is then said to 

 be trilobed. Fig. m becomes the middle lobe. Fig. j) the parapsides 

 scapuhe or lateral lobes. Fig. s is the meso-scutellum, usually desig- 

 nated as the scutellum, and has usually at the lateral basal angles (Fig. 

 ax) two snbtriangular sclerites termed axillte. Fig. nips is the meso- 

 Ijostscutellnm, often visible only as a transverse l)and, carina, or fold, 

 and again quite distinct and armed with one or more strong spines or 



