] 86 RITEBS OF SOTTTH A3IERICA. 



tion non interrompiie de 1400 lieus sans sortir du 

 domain des etablismens monastiqnes," -writes Hum- 

 boldt ; and what a field is there not here, without 

 crossing the boimdary from compararive civilization, 

 for eyerv species of inyestigation. Again, the same 

 author states, " Le Cassiquare, par example, forme 

 une ligne navigable entre denx bassuis de rivieres 

 (FAmazone et TOronoqne) dans Tarea est a 190,000 

 lieTi^-<^rrees. La temperatore, la profondure, et la 

 Vitesse des eaux, lenr limpidite, leur proprietes chi- 

 miaues. le lit des flenves tantot bossnx, tantot rem- 

 pli d eeueils influent puissant sur I'organization 

 animale.* If arranorements can be made to exceed 

 these bounds, and to trace these rivers to their 

 scources, there is another as extensive field entered 

 npon, and ground altogether uubroken to be sur- 

 veyed. The dangers and difficulties are undoubt- 

 edly great, but the rewards just as undoubtedly 

 certain. After making these remarks, and b-efore 

 closing the volume, we have thought it right to bring 

 together a few of the species observed by Humboldt 

 and more lately by D'Orbigny, and which do not 

 seem to have occured to 3Ir. Schombtu^k ; so that 

 as little of our present knowledge as possible may 

 be withheld from future investigators ; and we shall 

 take them in the order which has been already 

 followed. 



Among the Loricarinae and Silurid^e, with which 

 we commenced our first volume, we introduced a 

 short notice of most of the allied fishes which should 



I 



