195 



lake, the so-called "Shallow Lake," which is situated in the 

 Chodjen district of the province of Samarkand, near the Syr- 

 Daria station of the Central Asian railway ; it lies in the middle 

 of the " Starvation Steppe," not far from the right bank of 

 the river Syr-Daria. The water-plants found there are Vallis- 

 neria, Ceratophyllum, Potamogeton, Myi-iphi/Jlum, Najas, Cliara 

 and various others. The numerous small fish found in the lake, 

 as well as various rapacious water insects, such as Corixa, 

 Naucoris, Notonecta, Ranatra, etc., or the larvae of Epitheca, 

 Cordulia and Agrion or of Chloe and Ephemera, do not interfere 

 seriously with the existence in the waters of A. pulcherrimiis, 

 and the author found larvae in this lake continuously during- 

 the six months from April to the middle of October. There 

 are, however, times when they more or less disappear, namely, 

 when the lake is full or when the water is very low. During the 

 former period the depth and area of the lake increases consider- 

 ably, thus destroying the favourable conditions for the develop- 

 ment of the insects. At the second period, at the end of the 

 summer, various weeds (Aphouotheca gelatinosa, Anabaena 

 lemineniianni, Arthrospira gommontiana, Lijiighya kutzingii, 

 Rividaria natans and others) grow in large quantities and make 

 it impossible for the larvae to live. The most favourable time 

 for their breeding in the lake is the time after high water, 

 when not only the usual conditions in it are restored, but also 

 algae make their appearance on which the larvae feed. 



The development of the larvae in August and September in 

 the aquarium at a temperature of 19° R. (75° F.) requires about 

 3 weeks, while in June and July, at a temperature of 26° R. 

 (90° r.), it takes about 2 weeks. The development of the pupae 

 does not take more than 2 to 3 days. 



In addition to algae, dissection has revealed in the stomachs 

 of the larvae the presence of various other forms of aquatic life : — 

 Chlorella, Polyedriu7n,Chloreste'nu7n, Oscillaforia, and especially 

 Cymatoplevra solea, Cocconeis, Navicula, Epithemia gihha, Nitz- 

 schia siginoiclea, Cymbella and others; there were also found 

 remains of deep water plants and infusoria. The insect winters in 

 Turkestan in the larval stage, and not as an imago, as is the 

 case in India. The author comes to this conclusion, firstly, from 

 the fact of having found, on the 14th xVpril, 90 full-grown larvae, 

 as well as pupae; and secondly, because in autumn there are 

 mostly found quite young or half-developed larvae. This was 

 definitely proved in 1912, when the author visited Turkestan 

 in the winter and found there in December wintering larvae of 

 A. pulcherriTnus . Some larvae taken by the author to St. Peters- 

 burg in 1911 hibernated in the aquarium in the same stage. 



The author reports that some larvae in his aquarium stood 

 quite well a temperature of 7"5° E. (49° F.), followed by freez- 

 ing of the water in the aquarium, and only died in January 

 1912 because of the sudden rise in the temperature, after the 

 frost of -11° R. (-7° F.) which took place the day before. 

 During the author's investigations in Turkestan in the winter 

 of 1912 he did not find (on the Starvation Steppe and near the 

 "Shallow Lake") any images of .4. pulcherrimns, although he 



