Life-history of Dasylielea obscuva, W'lanertz. 581 



series of lonj? setae of brown colour, which in places are 

 superposed with the setse of the ventral sclerite. 



(3, 4) Two lateral wing-like sclerites (7.) are articulated 

 with the dorsal sclerite and serve for attachment of well- 

 developed muscles. They are not evenly chitinized, and 

 show clear and dark patches of chitin. Tlie whole structure 

 is connected with labium by means of two forked cliitinous 

 rods (/•(/, ), which lie in the lateral walls of the buccal cavity. 

 It is difficult to say, at present, if all the above-described 

 sclerites form the hypopharynx, or if the latter is formed 

 only by the ventral plate. This can only be settled by a 

 comparative study of this structure in several other species 

 of Dasyhelea and the closely-allied genera like Culicoides and 

 Forcipomyia. 



(b) The Thorax. 



The thorax is composed of 3 segments of brownish colour ; 

 the latter is due to the brown granules filling the peri[)heral 

 fat body-cells which line the hypodermis ; clear unpigmented 

 spaces remain only in the areas occupied by the imaginal 

 discs of wings, halteres, and legs. The segments are fur- 

 nished with a series of sensory hairs and pits, among which 

 special attention must be given to the 6 groups of ventral 

 sensory organs representing the remains of the thoracic legs 

 of Dipterous iarvse. Each sensory group (PI. XX. fig. 16) is 

 composed of two long hairs and 2 pits connected with the 

 imaginal discs of thoracic legs. 



(c) The Abdomen. 

 The 7 first abdominal segments show a brownish colo- 

 ration, due to the underlying fat body-cells, which, being 

 more or less regularly distributed, produce a pigmented 

 pattern characteristic of this larva (Pi. XX. fig. 9). These 

 segments bear also a few sensory hairs and pits. The last 

 abdominal segment is double; its anterior portion differs 

 very little from the previous 7 abdominal segments, while 

 its posterior portion has a very characteristic structure, which 

 will be described below. It bears posteriorly the anus and 

 a series of strong chitinous hooks bent anteriorly. Eight of 

 these hooks, disposed in 2 groups of -i, are ventral (PI. XX. 

 fig. 13), while 2 pairs of similar hooks are dorsal in })osition 

 (PL XX. fig. 12). Two small conical soft papillpc are seen 

 among the hooks on the ventral sides. Laterally and close 

 to its anterior boundary this segment shows two transverse 

 elliptical transparent prominences (PI. XX. fig. 11, p.). The 

 space between the large hooks show a few rows of small 

 dark booklets or spines bent anteriorly. By pressing a 



