1. TRÄGÅRDH, METAMORPHOSIS AND BIOLOGY OF ORCHESTES. 17 



The mandibles (Figs. 18 & 19, Pl. TI) are of the same 

 type as those of O. populi, with double terminal tooth ; the 

 teeth are however blunter than in that species. The inner 

 edge is thin and shghtly wavy. Two hairs. 



The maxillse (Fig. 7, Pl. II) resemble those of O. 

 populi; the lobus is more rounded at the top and provided 

 with much shorter and stouter bristles arranged in a row of 

 6, the palps are two-jointed, with short conical terminal 

 joint, truncated at the top. 



The labium (Fig. 10, Pl. II) is deeply constricted a 

 little in front of the middle; the anterior edge has numerous 

 rows of small cuticular teeth, arranged in transverse rows; 

 the palpi as usual single-jointed, very short, scarcely longer 

 than they are wide at the base and ventrally, a t the top, 

 provided with 4 — 6 small sensorial processi 



The antennse (Fig. 15, Pl. I) are of -the usual shape, 

 with a thin-walled, concentrically striated oval appendage, 

 heside which there are 3—4 smaller conical processi. 



The thorax (Fig. 13, Pl. I); the thoracic segments are 

 lower and shorter than those of the abdomen, and taper 

 gradually forwards. They ha ve neither the broad dorsal pro- 

 jections nor the veruciform lateral ones of the abdominal 

 segments. The prothorax is as in O. fagi and O. pojmli pro- 

 tected by shields, two dorsal and three ventral ones. They 

 are almost black and of very irregular form, their margin 

 being provided with numerous incisions. 



On the meso-and metathorax, at the places where the legs 

 would be found, if there were any, the cuticular teeth 

 coalesce to a pair of small irregular rings, ^ which probably 

 are of some use in locomotion. 



. On the sides of these two segments we notice a pair 

 of narrow almost crescent-shaped areas, where there are no 

 cuticular teeth, and which consequently are quite white. 



The abdomen (Fig. 13, Pl. I) consists of 10 distinct 

 segments, of which the 1st to the 7th are of even width, 

 whereas the 8th to the lOth taper gradually and rapidly 

 backwards and together form a cone. 



^ I suppose that the two pairs of dark spöts, which are noticeable 

 on Mjöberg's fig. 1., are these rings; M. however does not tell iis, whether 

 the larva is figured on dorsal or ventral view. 



Arkir för zoologi. Band (>. N:o 7. 2 



