185 



16. Head subquadrate ; abdominal segments with a number of rounded 



transverse ridges Platyuridae (p. 260) . 



— Head elongate ; abdominal segments without transverse ridges 



Mycetophilidae (p. 248) . 



17. Abdominal segments not subdivided . . . '. 18 



— Abdominal segments subdivided by means of transverse constric- 



tions . . 19 



18. Larva very slender, tapering towards the extremities, without 



thoracic or anal pseudopods or surface hairs except about 8 at 

 apex of abdomen, aquatic in habit; or stout, with well-defined 

 segments which are armed with strong bristles, some of which are 

 lanceolate ; pseudopods present ; terrestrial, living in manure or 

 under bark, etc Ceratopogonidae (p. 281) . 



— Larva rarely very slender, generally of an almost uniform thickness, 



rarely with the thoracic segments appreciably swollen but not 

 fused ; abdominal and thoracic segments frequently with rather 

 noticeable soft hairs, the last segment almost invariably with a 

 conspicuous tuft of hairs on dor.sum near apex ; pseudopods al- 

 most always present, sometimes only the thoracic one distinguish- 

 able in terrestrial forms-which are very rare 



Chironomidae (p. 284) . 



1 9. Body slender, tapering ; abdominal segments each with a single con- 



striction near anterior margin ; apical segment either with 5 short 



terminal processes or without distinct processes 



Rhyphidae (p. 241 ) . 



— Body stout, of uniform diameter; abdominal segments each with 2 



distinct constrictions ; apical segment with 4 rather long processes, 

 the low^er pair longer than the upper. .Limnobiidae, pt. (p. 207). 



pupae 



1. Head with several strong thorns in a vertical series on the median 



line ; pupae enclosed within galls on various parts of plants .... 

 Cecidomyiidae, pt. (p. 293) . 



— Head Avithout strong thorns, or if at base of each antenna there is 



a protuberance it is not sharp and thorn-like, and the pupae are 

 not enclosed in galls on living plants 2 



2. Pupa enclosed within a tough, parchment-like envelope consisting 



of the hardened larval skin, which resembles a muscid puparium. . 

 Cecidomyiidae, pt. (p. 293) . 



— Pupa free, or if enclosed it is within a cocoon which is not parch- 



ment-like and does not resemble a muscid puparium 3 



3. Thoracic respiratory organs sessile ; abdomen without strong thorns 



or leaf -like elevations ; legs straight 4 



— Thoracic respiratory organs stalk-like, or if sessile the abdomen has 



strong thorns or leaf-like elevations, or the legs are recurved 

 against base of abdomen and apex of thorax, or the coxae do not 



