Occasional Papers of the Museum of Zoology 39 



far back into the hills, where it is a beautiful little stream 

 flowing in a rocky and gravelly bed, with pools and waterfalls. 



On the Rio Mazamba, where we spent only a short time, 

 and that only on its lower courses near the railroad, we took 

 only Hetaerina caja and miniata, the former common, the lat- 

 ter represented by a single specimen. On the Rio Sardanilla, 

 where we collected more carefully, we found a Hetaerina 

 fauna very rich in species, if not in individuals. On not to 

 exceed two or three miles of its course we took nine Hetaerina 

 caja, five fuscoguttata, eleven macro pus, and one miniata. 

 Unfortunately, we failed to notice if there was any particular 

 distribution of these species on the stream. 



36. Rockstone, on the Essequibo River and on the Wis- 

 mar-Rockstone railroad, British Guiana. Elevation not noted. 

 Just east of the hotel is a large log-jammed creek, fifteen to 

 twenty feet wide in low water. A short distance below the 

 railroad station is a small, muddy creek, nearly dry, a succes- 

 sion of stagnant pools with no running water. On the large 

 island in the Essequibo opposite Rockstone is a similar but 

 drier muddy creek bed. Collected February i, 2 and 14, 19 12. 



Hetaerina domimila was taken on the large creek just east 

 of the hotel and nowhere else. Only fourteen specimens were 

 taken. A few laesa were collected on the small creek below 

 the railroad station, and a larger number on the island, where 

 also the single specimen of morihunda taken at Rockstone was 

 found. Hetaerinas were rather rare at Rockstone, our total 

 catch numbering only thirty-six specimens. 



37- Salom, Venezuela. A town on the road from Bejuma 

 to Nirgua. Conditions similar to those at Bejuma. Collected 

 the small, sandy and gravelly river near town for a few hours 

 on February 25, 1920. The water of this stream eventually 

 finds its way to the Orinoco. 



