20 HYMENOPTERA. 



each segment with a large ovate spot on each side, beneath 

 spotted as above ; the apical ventral plate angular at the apex, 

 which terminates in a curved spine. 



Hab. Western Australia. 



37. THYNNUS ASSIMILIS. B.M. 



Male. Length 8-9 lines. Closely allied to T. melleus - f but 

 the clypeus is not so much produced, and the process at the 

 apex of the terminal ventral plate is truncate ; in T. melleus it 

 has an acute spine at the apex ; the apical segment above is 

 punctured in the latter insect, in the present it is longitudinally 

 striated. The clypeus, mandibles, orbits of the eyes, hinder 

 margin of the vertex, and two spots at the insertion of the 

 antennae, yellow ; the yellow line round the orbits of the eyes 

 interrupted at their summit. Thorax black ; a line at the an- 

 terior and posterior margins of the prothorax, two longitu- 

 dinal lines on the disk of the mesothorax, one over each tegula, 

 two spots on the scutellum and one at each of its basal angles, 

 the post- scutellum and an oblique spot on each side, two oblique 

 lines on the metathorax and a small square one at its apex in 

 the centre, yellow ; the tegulae and some irregularly-placed spots 

 beneath the wings yellow; wings hyaline, the nervures ferru- 

 ginous. Abdomen yellow, with a line down the centre, which is 

 black at the base, becoming ferruginous towards the apex, and 

 similar transverse lines at the basal and apical margins of all the 

 segments ; the legs ferruginous. 



Var. 1. The abdomen ferruginous, with black lines as above. 

 Hab. Australia (Swan River). 



38. THYNNUS AGILIS. B.M. 



Male. Length 11 lines. Head and thorax black, abdomen 

 reddish-yellow ; the clypeus, a line at the inner and outer margins 

 of the eyes interrupted at their summit, and two oblique spots 

 between the antennae and the mandibles, yellow. Thorax : the 

 posterior margin of the prothorax, a spot on the scutellum, the 

 post-scutellum, the tegulae, and legs, yellow; the legs with a 

 ferruginous tinge on the femora and tibiae beneath; wings 

 hyaline, with a faint yellow tinge, the nervures fusco-ferrugi- 

 nous ; the metathorax swollen at the sides, rounded behind, and 

 covered with hoary pubescence, the other parts of the thorax 

 as well as the head with a short thin hoary pubescence. The 

 base of the abdomen and the basal and apical margins of all the 

 segments blackish-brown ; each segment has on each side a large 

 ovate macula nearly the width of the segment, and nearly meet- 



