36 Rio Agua Dulce April 7 My best theory demands that there is a good bit of ecological overlap & competition between nigricand- ates and chiapensis. They are zonally separated at Esmeralda according to Brockkoller and certainly they are absent whenever chiapensis is present in any numbers. No letters from Brockkoller (1954) It will be important to determine whether humilis can occupy "rich" vegetation when chiapensis is not abundant. If this is true it would explain humilis' absence from Tonalá proper. If it can occupy habitat similar to that of chiapensis then may also be ecological competition between the two. April 8 Rode out in the morning to the Rio Los Limones, 8mi. NW Tonala', after crossing a small dry stream 4mi.NW. Parked car and hiked SW along the river.