858 EXPERIMENT STATION RECORD. [Vol.40 



sentatlve. The average incidence in school children taken as a unit invariably 

 equaled that of the community as a whole, indicating strongly their availability 

 for experimental index work and the obtaining of data." 



Effective malaria control in a rice field district, with observations on ex- 

 perimental mosquito flights, J. C. Gek;er. W. C. Pobdy, and R. E. Takbett 

 (Jour. Amer. Med. Assoc, 12 (1919), No. 12, pp. 8J,4-8.' f l, fig. 1).— "Malaria has 

 been eliminated from a typical rice field district. The question of flight of 

 Anopheles qvadrimaculatus may of necessity be regarded from two angles, that 

 of experiment and that of observation. In one, the largest experiment of its 

 kind ever undertaken in the United States, we have a record flight of 1 mile. 

 In the other observation, there has been recorded continuously and on dif- 

 ferent occasions a flight of 1.7 miles. 



"The use of 10 grains of quiniu sulphate by mouth for sterilization of the 

 blood of malaria carriers is evidently cllicient for one malaria season if used 

 actively over a period of 30 days. 



"The completely negative clinical history of the 19 malaria carriers dis- 

 covered on microscopic examination indicates, on the one hand, an Immense 

 difficulty in obtaining complete malaria control, but emphasizes, on the other 

 hand, the importance of the detection of the human carriers." 



A revision of the genus Sciara of the family Mycetophilidte. V. W. I'kttey 

 {Ann. Ent. Hoc. Amer.. 11 (1918), No. 4, pp. 319-.i.y>, pit. J i.— Thirty species 

 are described by the author as new, of which seven belong to the genus Sciara 

 and 23 to the new genus Neosciara. Two additional species of BClarlds from 

 South America are also described as new. 



A contribution to the knowledge of the botflies, Gastrophilus intestinalis, 

 G. hsemorrhoidalis, and G. nasalis, S. U.vdwkn and A. E. CaiceboH (Bui. Ent. 

 Research, 9 (1918), No. 2, pp. 91-106. pi. 1, figs. 10).— "Th- of the three 



species of botliies discussed in tins paper are distinguished by the fact of that 

 of G. hwmorrhoidalis being the only one stalked. It is also longer than those 

 of the other two species, which are of about equal length. Further, it is 

 brownish black in color, that of G. intestinalis being whitish yellow and G. 

 nasalis yellow. The egg of (/'. intestinalis adheres to the hair by clasping 

 flanges, which run only two-thirds of its length, whilst the flanges of the G. 

 nasalis egg run almost the entire length. 



"The egg of G. hamorrhoidalis is not inserted nor screwed into the skin of 

 the host. The eggs of G. intestinalis are laid indiscriminately on the body of 

 the host, but preferably on the long hairs investing the inside of the foreleg. 

 G. nasalis lays its eggs on the hairs of the intermaxillary space and G. kamor- 

 rhoidalis on the hairs of the lips, preferably the lower. 



"Of the recently emerged larva, that of G. intestinalis is Largest in size and 

 G. hcemorrhoidalis smallest. In these two species there are 13 body segments, 

 whilst G. nasalis has but 12 and is the only one bearing slender, elongate hairs. 

 The larval posterior spiracles of the latter species arc sessile; whereas in the 

 others the two spiracles are borne on the distal ends of two cylindrical pro- 

 cesses arising from the ultimate abdominal segments. 



"The eggs of O. intestinalis do not readily hatch unaided, but apparently 

 require the application of moisture and friction or shock, A large number of 

 C. nasalis eggs hatched spontaneously and a few of the O. hcmorrhoidalis i 

 also. This latter fact is regarded as supporting the theory that the newly 

 emerged larva? of these two species may penetrate directly into the integument 

 of the host. The lesions on the skin of the Intermaxillary space and lips of 

 the host observed at the time the eggs were hatching may be due to direct pene- 

 tration of the larva) of O. nasalis aud G. haniorrhoidalis. respectively. The 



