228 



MOSQUITOES OF NORTH AMERICA 



to note, also, that at this time two of the largest pools which were situated 

 close by, and have been described as swarming with mosquito larvae, had been 

 filled in with sand. Samples of water taken from various parts of the town were 

 examined for the amount of chlorine present in them, the result is given in the 

 following table. 



' Sample of Avater. 



1. Public well, New Town, no mosquitoes present 



in water 



2. Public well, Lancaster Street, water rather foul. 



Anopheles larvae present in numbers 



3. Public well in Clifton Road, behind Hospital, no 



larvae present 



4. Water (tidal) found in drain near sluice gate, 



Blucher Street, A. costalis and large quantities 

 of C. halassios present 



5. Small well in private garden, Culex present, few 



only 



6. Small well in native compound, Victoria Street, 



Culex larvae present 



I 



Chlorine per 

 100,000 parts. 



'Chlorine expressed 



as percentage 



of NaCl. 



161.2 



1148.0 



186.0 



1 038 . 5 



27.9 



1145.0 



.265 

 1.89 

 0.3 



1.71 

 0.04 



1.88" 



To refer briefly to the other records of Anopheles breeding in sea-water, this 

 habit was probably first mentioned by Grassi, who observed it at Metaponto, 

 Italy. Nuttall, Cobbet and Strangeways-Pigg captured larvae six times in 

 brackish water. A. Clerc has experimented with larvae of Anopheles maculi- 

 pennis; he found that larvae placed in water with 44-46 grammes of salt to the 

 liter would die if very young, but the older larvae developed and produced imagos. 

 Christophers and Stephens found Anopheles larva to occur at Accra in brackish 

 pools 0.6 per cent salt. Foley and Yvernault found that in Algeria Anopheles 

 chaudoyei breeds in saline water containing 40 grammes of salt to the liter. 

 Chatterjee found larvae of what he called Anopheles rossi, but which it would 

 now seem were A. ludloioii, in brackish water in India, Gholap found another 

 Indian species. Anopheles stephensi, breeding in salt water. 



In America several species of Anopheles have been found to breed in brackish 

 water, but none of them exclusively so. Chapin, in Ehode Island, found Anoph- 

 eles larvae living in brackish water on the coast. Anopheles crucians has been 

 found to breed in brackish water in New Jersey and Louisiana, and we have 

 already mentioned that Smith has found larvae of A. quadrimaculatus in New 

 Jersey under similar circumstances. It is worthy of note in this connection that 

 Anopheles crucians seems to thrive best in the vicinity of tide water and to occur 

 much less abundantly inland. 



Anopheles albimanus, of tropical America, according to information furnished 

 by Mr. A. H. Jennings of the Isthmian Canal Commission, breeds in strongly 

 brackish water as well as in fresh water. The same may be said of Anopheles 

 tarsimaculata, a geographic form of A. albimanus, and of A. argyritarsis. This 

 last statement is made on the authority of Peryassu. The Brazilian observers 

 made a series of laboratory experiments to determine the degree of salinity in 

 which these larvae could develop to imagos. They found that in slightly brackish 



