232 Mr. Lubbock on the 



XXIII. On the Freshwater Entomostraca of South 

 America. By John Lubbock, Esq., F.Z.S. 



[Read May 7lh, 1035.] 



Professor. Dana, in his great work on the Crustacea collected by 

 liim in Captain Wilkes's expedition, has devoted a long and most 

 interesting chapter to the geographical distribntion of these animals. 

 Great, however, as have been the pains he has bestowed on it, and 

 many as have been the facts at his disposal, yet there are so many 

 species yet to be described, and the geographical limits of those 

 which are described are so little known, that it must be confessed 

 that he excites rather than satisfies the interest of Naturalists. 

 Also, as might have been expected, attention has been more 

 directed to the higher and larger families than to the smaller and 

 lower ones, which are both more rich in species, and have hitherto 

 been less studied. 



The freshwater provinces have necessarily more definite 

 boundaries than the marine, because it is more difiicult for fresh 

 water species to migrate, or be accidentally carried away from 

 their native haunts. For these reasons I was anxious to examine 

 the Crustacea collected by Mr. Darwin in the rivers and lakes of 

 South America. It can hardly be doubted that, when thoroughly 

 examined, they will prove as rich in Entomostraca as our own ; but 

 owing to the meshes of Mr. Darwin's nets being too large, and to 

 his attention not being especially directed to Entomostraca, I only 

 find five species in his Collection, and one of them is so much in- 

 jured that I cannot describe it. Professor Dana, in his great 

 works, describes three species; Mr. Gay, in ([\e Fauna Ch'ilena, 

 six; and Dr. Baird, in the Proceedings of the Zool. Soc, one; so 

 that the list is at present as follows : — 



Cypr'ts Donnettii, Baird. 

 ChUensis, Dana. 

 speciosa, Dana. 

 /tuslralisy mihi. 

 Brasiliensis, mihi. 



