THE CANADIAN ENTOMOLOGIST. 199 



quote them in this paper. The Diptera he has studied seem to fall into 

 two groups, those where the antlia or pumping stomach is simple, and 

 those in which it is divided by a semisphincter muscle into two parts, the 

 latter being the case with the more primitive forms, while among the higher 

 forms (Dolichopodidse, Muscoidea, etc.), the posterior division is wanting. 

 In Corethra, Simulium, the I'abanidae, Bombylidae, Therevidse, Asilidse, 

 etc., the preneural and the postneural parts of the antlia are thus divided, 

 no trace of the separating semisphincter muscle being found in Culex or 

 Anopheles. There are in Corethra four anterodorsal dilator muscles 

 instead of two as in Culex and Anopheles. It has, like these, three 

 oesophageal diverticulse, but only four rectal papillae, where these possess 

 five. Furthermore, Mr. Thompson finds that Corethra differs from Culex 

 and Anopheles in having the hypopharynx connate with the labium in 

 both sexes ; possessing four instead of five malpighian tubules ; simple 

 instead of tripartite salivary glands ; no clypeus, this being replaced by 

 an oval sclerite ; and no " proboscis canal." He remarks that the internal 

 characters would seem to indicate that Corethra is neither a Culicid nor a 

 Simuliid, but a lateral branch low down on the Culicid stem ; the larvae, _ 

 which lack flabellaj and differ in rostrum, place of attachment of antennse, 

 presence of air floats, form of body, division of foregut, etc., tend to confirm 

 this. He at present regards the evidence, while pointing to a close 

 relationship of Corethra to Anopheles and Culex, and showing notable 

 relationship between Corethra and Simulium, as indicating that Corethra 

 and Anopheles have the same common ancestor, the former and more 

 primitive branching off at a lower point on the ascending scale, while Culex 

 may be derived from Anopheles. Would there be any gain by merging 

 such heterogeneous elements as Culex and Corethra in the same family? 

 Likewise, why should the Dixidte, whose wing-veins are bare of scales, 

 and whose larv;e and pupje difter so from those of the Culicida:', be included 

 with the latter? .^.mong the Dixidee the antenna? of the adults are almost 

 bare, and are quite similar in the two sexes, whereas in the Corethridae, and 

 with but one known exception in the Culicid?e, they bear long hairs, which, 

 except in a few Culicid cases, are longer and much more numerous in the 

 antennae of the males than in those of the females. The subcosta of the 

 Dixidae is short, reaching only to a point opposite the first branching of 

 the radius ; in the other two families it is prolonged nearly half its length 

 beyond the first branching of the radius. Moreover, tlie larvae of the 

 Dixidae are distinguished by having the three thoracic segments always 

 distinct and by two pairs of fleshy appendages, resembling prolegs, on the 

 first and second abdominal segments, no trace of anything like prolegs 

 being found in either of the other two families. The pup^e are inactive, 

 floating quietly on the surface. 



