588 LOUIS AGASSIZ. 



and the brackish marshes would be equally 

 desirable ; another from the river at Valencia, 

 and, if possible, also from its head-waters at 

 Ternel; another from the river Segura at 

 Murcia, and somewhere in the mountains 

 from its head- waters. Granada would afford 

 particular interest as showing what its moun- 

 tain streams feed. A collection from the Al- 

 meria River at Almeria, or from any of the 

 small rivers of the southern coast of Spain, 

 would do ; and it would be the more interest- 

 ing if another from the river Xenil could be 

 obtained at or near Granada, to compare with 

 the inhabitants of the waters upon the south- 

 ern slope of the Sierra Nevada. 



Next would come the Guadalquivir, from 

 which a collection should be made at San 

 Lucar, with the brackish water species ; an- 

 other at Seville or Cordova, one among the 

 head-waters from the Sierra Nevada, and an- 

 other from the mountains of the Mancha. 

 From the Guadiana a collection from Villa 

 Real, with the brackish species ; one from 

 Badajoz, and one from the easternmost head- 

 waters, and about where the river is lost un- 

 der ground. 



The Tagus would again require an exten- 

 sive exploration. In the first place a thorough 



