ON SALT WATER INSECTS. 



45 



pair, which latter are seen beneath the mesothorax of 

 the larva. At this time, also, can be seen the secondary 

 tracheal branches, a pair for each abdominal segment. At 

 a later stage, just prior to the moulting of the larval skin, 

 the head and all the limbs and the wings are free from the 

 body. After the skin is moulted the head of the pupa (Fig. 

 3, (?, front view) is bent down upon the breast, and the 

 limbs and wings folded closely to the body. The short 

 autennte are curved beneath the eyes, while the long slen- 

 der legs are folded and curved up beneath the extremities 

 of the wings. The body of the pupa is straightened out, 

 the long slender abdomen being but very slight^ curved. 

 The head is sunken in the full, much roimded thorax. The 

 wings are rather 

 narrow, and the 

 abdomen rather 

 slender. There are 

 no thoracic fila- 

 ments, nor is the 

 abdomen termi- 

 nated with hairs. 



but the genital ar- 

 mor is well devel- 

 oped, as shown in 

 our figure. In 

 these respects the 

 pupa seems to dif- 

 fer from what we 

 suppose to be the typical forms of Chironomus. 



Imago. $. (Fig. 4, with head of ?.) The antenna3 

 of the male are about as long as the thorax, arising from 

 a large knob-like basal joint ; the joints are of even 

 length, and from each one arise long, delicate hairs, 

 which in our specimens were somewhat appressed to the 

 antennae, as shown in the figure, but we think it was 

 owing to the immaturity and dampness of the specimen, 

 and that the hairs stand out as usual in the genus. The 

 lingua is short ; palpi well developed, incurved ; eyes 

 large, globose, prominent, black. The body is through- 

 out pale testaceous ; on the anterior half of the thorax 



