DISTRIBUTION OF FISHES IN SPAIN. 589 



collection of all the species found in the great 

 estuary ought to be made with the view of 

 ascertaining how far marine Atlantic species 

 penetrate into the river basin ; then one from 

 Santarem, and another either from Talavera 

 or Toledo or Aranjuez, and one from the 

 head-waters in Guadalaxara, and another in 

 Molina. 



The collections made at different stations 

 ought carefully to be kept in distinct jars or 

 kegs, with labels so secure that no confusion 

 or mistake can arise. But the specimens col- 

 lected at the same station may be put together 

 in the same jar. These collections require, 

 in fact, very little care. (Here some details 

 about mode of putting up specimens, trans- 

 portation, etc.) If the same person should 

 collect upon different stations, either in the 

 same or in different hydrographic basins, the 

 similarity of the specimens should not be a 

 reason for neglecting to preserve them. What 

 is aimed at is not to secure a variety of spe- 

 cies, but to learn in what localities the same 

 species may occur again and again, and what 

 are the localities which nourish different spe- 

 cies, no matter whether these species are in 

 themselves interesting or not, new to science 

 or known for ages, whether valuable for the 



