42 



MEMOIRS OF THE CARNEGIE MUSEUM 



The first day of October until evening was devoted to sorting and preserving 

 fishes. Prochilodus gave us much trouble. Full strength alcohol and formaline 

 injected did not keep these specimens from beginning to decay. In the evening we 

 seined on the rocks of the stelling and in the railroad-cut mentioned above. At the 

 stelling we caught so many Hemidoras carinatus and allies with erected spines that 

 it took us a long time to untangle them from the net. Each pectoral spine of these 

 catfishes is provided with retrorse hooks, the spines are erected when the fish feels 

 himself caught, and each spine must be individually disentangled from the net. 



On the second of October we went to the Rockstone sand-bar with our two 

 Indians. We were soon joined by seven porters who came from Rockstone to get 

 sand and who helped us pull the large net at the lower end of the sand-bar. The 

 most important captures we made consisted of specimens of Geophagus carrying young 

 in their mouths. The outer edge of the bar was almost barren, but yielded a few 

 minute, translucent specimens of Characidium, which so closely resemble our sand- 

 burrowing darters that they amply repaid for the water-hauls. But the greatest 



Fig. 12. Edge of bayou between right bank of Essequibo and outlying sand-bar at Rockstone. 



success was obtained in a bayou between the upper half of the bar and the land. 

 Here we collected a large number of small fishes. The Indians took half a bushel. 

 There is a great general similarity between the contents of the net here and one 

 drawn at any similar locality in the Mississippi valley, although not a single species 



