350 THE CANADIA.N ENTOMOLOGIST. 



effort, and when this ceases are immediately carried to the top. Dr. Dyar 

 has pointed out to me that the pupae of Aedes atropalpus and Stegomyia 

 calopiis can remain below the surface at any depth without effort, and 

 therefore, their specific gravity must be the same as that of the water. In 

 the case of Stegomyia calopus this is obviously of great advantage, and 

 even essential, to the preservation of the species. As is well known, this 

 species breeds almost wholly in water in artificial receptacles, in the 

 tropics primarily in the jars of drinking water kept in every house. When 

 water is poured from the jar the pupae go to the bottom, and remain there 

 until the danger is over. The pupae of other mosquitoes could not remain 

 below, and would be poured out with the water. With reference to any 

 classification by pupal characters, it must be further stated that the pupae 

 of Corethra and Eucorethra are unlike those of Sayomyia, and practically 

 like those of Culicines, both in appearance and behaviour. Pupae 

 essentially similar occur also in the Chironomidae, and the pupa of at least 

 one species of Dixa that I have bred is in every respect like that of a 

 Culicine. In the family Psychodidae the pupae are for the most part 

 active. The pupa of an unidentified species of this group, sent to us from 

 Florida, is free swimming and active, .and greatly resembles that of a 

 Culicine. In the Psychodid genus Mariana, on the contrary, the pupa 

 is inactive, and attached to rocks in moist situations. 



As to the eggs of the Corethrids, so far we know only the eggs of 

 Sayomyia, and these are suspended in a mass of gelatinous substance. It 

 is quite likely that those of the other genera of Corethrids are not deposited 

 in this way. Eucorethra occurs so sparingly that the eggs must be laid 

 singly. The indications are that Corethra hibernates in the egg, and if 

 in a gelatinous mass the eggs would hardly be in a suitable condition to 

 withstand freezing. A Culicine which Mr. August Busck has recently 

 discovered on the Isthmus of Panama deposits its eggs in a gelatinous 

 mass. According to Miss Mitchell's classification this mosquito would 

 become a Corethrid ! Turning to the Chironomidae, we find that although 

 many of the aquatic species deposit their eggs in a gelatinous secretion, 

 there are others that do not. Should these latter be put in a separate 

 family ? Mr. Coquilleti's unsatisfactory application, as a primary division, 

 of the mode of egg-laying of the Culicidae,^ illustrates with what caution 



3. D. W. Coquillett : On the breaking-up of the old genus Culex. Science, 

 N. S., XXIII, 312-314, 1906. 



