NEMATOCERA. 



49 



has undergone for fertilization by insects, and has called forth a great 

 deal of attention. The figure below shows the modifications. 



The distribution of the Cecidomyidce in space seems to be very 

 great ; most regions of the globe furnishing examples of this family. 

 They seem to extend into the Arctic Circle, but are more abundant 

 as we approach warmer climes. 



Their distribution in time is limited, as far as we know, the 

 tertiary ambers alone yielding tlieir remains. From these, two extinct 

 genera, Lithomyza and JMonodiciana, Lw., have been described. The 

 former belongs to the Anaretina, and the latter to the Cecidomyina. 

 About twenty-three species in all have been described, amongst the 

 sub-genera Epidosis,"^ Dirhiza, Diplosis, Cecidoinyia, and Asyiiapfa, 

 some from America and some from Europe. Lasioptera has also 

 been found in a fossil state in ^^'yoming. Their small size 'and 

 fragile nature would naturally hinder their preservation. 



Fic. II. — Aristolochia clematis, showing method of fertilization, i. Unfertilized 

 blossom. 2. Fertilized. A. Funnel. B. The flask with generative 

 organs. C. The ovary. 



The classification of the Cecidomyida^ is as follows. They can be 

 divided, according to Loew, into two sub-families : 



A. Cecidomyina = CecidomyincE^ Rd. 



Three or four longitudinal veins on wings, the last two often 



coalescing at the beginning of their course, forming a fork. Ocelli 



absent. 



B. Aiiareti/ia ~ Lestre/iiiiuv, Rd. 



Has a supplementary vein between the second and third of the 



Cecido/ziyina. This additional vein is furcate. Ocelli are present in 



most of this group. t 



* "Bernstein-Fauna," p. 32 Loew, descriptions of C. [Epidosis] incoinpL'ta 

 and C. ininiiiissinia. 



t Cccidogoua has no ocelli. 



