Mycctobia, Ditomyla, and SyinmcriH. 39 



formed me tliathehad found a specimcuof Si/minerun annu- 

 lata wliich had hatched in one of his hreedin^^-jars. " The 

 larvic of this species," ho tuhlcd in his letter, " were borin;^ 

 in a piece of rotten elm wood. They arc almost trans- 

 parent and f^hissy in appearance, and, like those of DUomijia, 

 move very little and very slowly. The pupie \vrif;;gle in an 

 almost snake-like manner when extracted from their habitat. 

 Unt'ortnnately I found that all the full-sized larvto had 

 pupated. I have one larva preserved in spirit." 



All the material Mr. Ivlwards could send me consisted of 

 an empty pupa with a moulted larval skin attached to it and 

 the larva preserved in spirit, mentioned in his letter. 



This was, however, quite sutHcient for the complete 

 morphological study of this larva. 



The larva of Symmcrus annuluta (PI. V. fig. 26) is 11 mm. 

 in length ; its last abdominal segment bears the posterior 

 spiracles, l)ut is without the dorsal [)aired prominences which 

 are present in Ditomyia larvae. Tliese two larvae are easily 

 distinguislied from one another by their colour and post- 

 abdomiiud prominences, but they are quite similar in the 

 detailed structure of almost all their organs. 



The anteniue (PI. V. fig. 32), labrum (tig. 27), mandibles 

 (fig. 31), maxillae (fig. 2^, m.x.), and labium (tig. 29, Lb.), 

 with their palps {m.p., Lp.) have the ssame structure as those 

 of Ditomyia larvc'e. The differences in detail of these organs 

 in these two larvic are shown in the above-mentioned figures. 



We may mention only that in the maxillary palps of 

 St/mmerus larvte we do Jiot find the lateral sensory pa[)illa 

 which is well developed in Ditomyia larvie (PI. 1\ . 

 fig. 17, I.S.). The labium in Symmerus larvae is more 

 rounded. 



The thoracic and abdominal segments also bear the 

 sensory hairs, and the remains of the thoracic legs arc 

 represented by three sensory hairs (fig. 30). 



The last abdominal segment is rounded. 



The respiratory system is peripneustic, with nine pairs of 

 functional spiracles : one prothoracic and eight abdominal. 



The spiracles (figs. 33 & 3J) are very small, and their 

 structure is similar to those of the first seven pairs of 

 abdominal spiracles of Diloinyin. 



ru|ite (fig. 28). Unfortunately I have only one empty 

 skin of a j)npo. I may mention, however, that tUe pro- 

 thoracic horns are more elongated than in the pupa of 

 Dilonn/ia, and that the thoracic segments bear a row of 

 lateral short hooks. 



