602 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



are attached, two-thirds of the length of cerci ; apex turned inward, 

 and recurved, not contracted. Spiracles well developed, finger- 

 shaped tubes diminutive on all segments. 



T. dubius is very close to the European T. formicarius Linnaeus 

 (fig. 79), but 2\ formicarius is about 16 mm., with cefrci very slightly 

 converging, almost parallel, only a trifle shorter than the distance 

 to the anterior margin of basal plate; distance between the outer- 

 sides of the cerci where these are attached, about equal to the length 

 of the cerci. 



THANASIMUS REPANDUS Horn. 



Hopk. U. S. No. 15431B ; mature. Species reared ; cast skin and imago preserved. 



Very similar to T. dubius and T. formicaHus; about 16 mm. 

 Cerci slightly divergent, a trifle longer than distance to the anterior 

 margin of basal plate; distance between outereides of cerci, where 

 these are attached, about equal to the length of cerci. 



Subgenus 2b. 



(Figs. 81-83.) 

 ENGCLERUS ICHNEUMONEUS Fabricius. 



Hopkins, U. S. No. 9194g; mature. Species reared ; cast skin and imago preserved. 

 (Figs. 17. 31, 47, 64, 81, 125.) 



Total length of body, about 11 mm. ; extreme width, about 2^ mm. ; 

 extreme thickness, about 2 mm. ; anterior width of prothorax a trifle 

 less than 2 mm. Corneous parts shiny, reddish brown, delicately 

 chitinized parts shiny, brown yellowish ; membranous parts crimson, 

 ventrally paler. Setae rather soft and long. Frons on each side 

 with two low cushion-like longitudinal elevations, one behind the 

 other; anteriorly a shallow groove behind angulus frontalis. 

 Mandible from apex to attachment of tendon of retractor muscle 

 about three-fourths the length of frons; length to width as 9:6; 

 apex slightly projecting over inner angle of basis; retinaculum a 

 trifle closer to tip than to basis of mandible; margin between re- 

 tinaculum and end of apex entire; two mandibular setae. Hypo- 

 pharyngeal plates laterally not extending beyond the bicuspidate end 

 of the vertical arm from stipes. Meso- and metathoracic dorsal 

 plates well developed. Basal plate of cerci about same length as 

 frons, a trifle wider than long. Cerci about same length as basal 

 plate, comiform, nearly parallel, distance between attachments not 

 much shorter than length of cerci; apex not contracted, turned in- 

 ward, slightly recurved. Spiracle on the eighth abdominal segment 

 annuliform-bifore with large fingershaped tubes. 



