312 A YEAR OF COSTA RICAN NATURAL HISTORY 



strip near the river, fairly low but rising in the air when I 

 tried to catch them in my net. {Miathyria is another rela- 

 tive of Tramea and has two cross-ridges on the third abdom- 

 inal segment but only one cross-ridge on the fourth segment; 

 Miathyria marcella Is one and one-half Inches long and Its 

 wing-spread two and one-half inches; the hind wings have 

 a brown band at the base which usually does not reach to 

 the hind margin. Like Tramea cophysa it is a widespread 

 species in the American tropics.) 



Close to the mouth of the river an arm — the Westfalia 

 Laguna — branched to the left (north). Up this I now 

 directed the boat, Mr. Brandon having been obliged to 

 leave us long before; the banks were lined with water-hya- 

 cinths {Eichhornia) which soon became so numerous that 

 the water's surface was completely covered. We forced 

 our way through them as far as the railroad bridge, beyond 

 which we could not go as a staging for repairs had been con- 

 structed beneath the bridge. We went back to the river, 

 stopping a few moments at the landing-stage of West- 

 falia Farmhouse which latter lies on the beach between the 

 sea and the laguna a few hundred feet north of the mouth of 

 the river. 



Just above the opening of the Westfalia Laguna into the 

 river, and on the same bank, was another, opening at both 

 ends into the river so as to form a side channel. We went 

 through this also. At some spots In it were millions of 

 small, almost totally transparent fish. At times, a whole 

 swarm of these fish leaped simultaneously out of the water 

 Into the air, giving the appearance of a wave. There were 

 many transparent prawns, about an inch in length, here also. 

 Among the water-hyacinths of the Westfalia Laguna, and to 

 a less extent along this second laguna, we took a number of 

 Enallagma cultellatum, a yellow, black and blue dragonfly of 

 small size, new to Costa Rica. Between this second laguna 



