10 AMERICAN HYMENOPTERA. 



the median beyond its union with the basal vein). In others 

 it is interstitial, or nearer the apex of the wing — postfurcal. 

 Transparent spots, called bullas, occur in the discocubital and 

 second recurrent veins. The discoidal and cubital cells are 

 confluent, and as there is no areolet this portion becomes a 

 sort of appendix. The third discoidal cell is in most Ophions 

 short and thick, but in O. costale, as in the other genera, it is 

 long and narrow. 



Posterior wing. — The only important character in the poste- 

 rior wing is the shape of the transvere median vein, or, as I 

 have called it — following the European writers — the nervel- 

 lus. This is broken in most genera, but in Ophiopterus it is 

 straight. In Thyreodon and Athyreodon it is broken well above 

 its middle, and in Ophion it is usually broken below the mid- 

 dle, but in a few species at or above this point. 



The frenal hooks are borne on the anterior margin in two 

 places, along the base of the radial cell and frequently near 

 the base of the median cell. The number varies consider- 

 ably in a species and often on the two sides of an individual. 



Tegulce. — The tegula is a small chitinous plate lying over 

 the base of and separating the anterior wing from the side 

 of the mesonotum and propleura in front and the mesonotum 

 above. Its surface is smooth or sparsely pubescent. In 

 Ophiomorpha the tegulae are rudimentary or wanting. 



Legs. — The legs are long and rather slender, the anterior 

 being shortest and the posterior longest. The coxae and 

 trochanters are unarmed, but are with the rest of the legs 

 more or less sericeous or pubescent. The coxae are large 

 and closely articulated with the body, the posterior being 

 usually larger. The shape is conical or subcorneal, with 

 the insertion of the trochanter dorso-apical. The unarmed 

 femora vary from each other only in size. The anterior 

 tibia is the only one which is shorter than its femur, and 

 bears at its apex, below, an articulated tibial comb. This, in 

 connection with a similar comb on the base of the first tarsal 

 segment, forms a cleaning apparatus often seen in Hymenop- 

 tera. Each of the median and posterior tibiae have two api- 

 cal spurs, of which the inner is noticeably longer. 



