104 Larval and Papal Stages of Bibiu Johaiiiiiw L. 



year, the larvae were kept under cover in a temperature which was 

 always above that outside. 



Although the larvae were found during the latter half of an unusually 

 severe winter, they appeared but little affected by the cold and did not 

 descend into the soil to any distance as far as was observed. 



No parasites were met with in connection with these larvae, and the 

 only reference to parasites met with in this family, is that of Malloch (15). 

 This observer mentions a hymenopterous parasite of whose connection 

 with this family of hosts he is uncertain. Lyonet mentions finding a 

 " louse " on a Bihionid larva, and a Filaria inside one. 



5. COMPARISON WITH LARVAE OF OTHER DIPTERA. 



The structure of the larva of Bibio Johannis indicates that it is very 

 primitive, the larva having twelve complete segments, a comparatively 

 large head that cannot be withdrawn into the first segment, and well- 

 developed mouthparts. 



The presence of ten pairs of spiracles is very unusual, and is character- 

 istic of the family. The fact that the spiracles of the first and twelfth 

 segments are considerably larger than those of the other segments seems 

 to indicate a tendency for the larva to become amphipneustic instead of 

 peripneustic. Of the mouthparts, the most noteworthy is the labium, 

 which is modified in a similar way to that of Chironomus and Dicra- 

 nota (16, 17). Three caeca is an unusual number, many caeca being found 

 in Chironomus, eight in Anopheles and a few other larvae, four in a 

 number of species, and two in others. 



The posterior caecum is also unusual although Dufour found a 

 "caecum lateral" in Tipula lunata, which, however, opened from the 

 intestine and not from the mesenteron as is the case in the Bibio Johannis 

 larva. Four is a compion number of Malpighian tubes, but they usually 

 enter the alimentary canal separately. 



The oesophageal valve is fairly primitive, considerably more so than 

 that of Simulium or Chironomus {i&, i~) or Anopheles (12). It considerably 

 resembles the valve figured by Holmgren (ii) in Mycetojyhila ancylifor- 

 mans, but is relatively shorter. 



The structure of the cardia is also similar to that shown by Holmgren, 

 in having first a regular epithelium of columnar cells, followed by a con- 

 si-derably folded region. In Bibio Johannis however there is a space 

 between the two parts of the oesophagus forming the valve, which 

 contains muscle fibres, and is more like that of Dicranota. 



