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collections made in Princeton and vicinity caught very few 

 Anopheles quadrimaculatus Say, although large numbers could 

 be taken at places in the territory. The writer is unable to 

 explain this condition except on the supposition that this species 

 does not fly in the early evening or during the day. It seems, 

 in view of this conclusion, the evidence from failure to find 

 malarial mosquitoes in the extensive collections of the Union, 

 Essex, Hudson, Bergen and Passaic Counties may not mean 

 that they are really scarce, but may merely mean that owing to 

 a difference in their habits we have failed to take them. 



It has occurred to the writer, and been many times suggested 

 to him, that a more careful investigation of the killifish as a 

 means of controlling the salt-marsh mosquities might result in 

 the finding of an efficient method of using them artificially. 

 With this in view the investigation was undertaken last summer, 

 and while the effectiveness of these creatures was again demon- 

 strated, no way in which they could be used artificially in a 

 practical fashion was found. It was developed, however, that 

 for nearly one month, mainly in August, the killifish become 

 sluggish and make no effort to spread themselves over the 

 marsh. If this habit is a general one and occurs season in. and 

 season out, it is obvious that even the drained marshes must be 

 carefully looked after during that period. 



The question of "Why cantator appears in the early spring 

 all along the coast and practically disappears through mid- 

 summer and leaving sollicitans in its place" was left unanswered 

 by the investigations of Dr. Smith. Opportunity came during 

 the past season to determine the cause, and the studies seem to 

 show that the degree of salinity of the water is the determining 

 factor. During the spring and early summer the salinity of the 

 waters at the edges of the marsh is low and conditions favorable 

 to the breeding- of the A. cantator are created, with the progress 

 of the season the salinity of the water in these places rises and 

 conditions favorable to the breeding of A. sollicitans come about. 

 In all sections of the salt marsh where the salinity remains low 

 throughout the year, as through the northern part of the Hack- 



