Gigantic Silurce. 309 



tributaries of the La Plata, and from that river itself. He ob- 

 served, however, but one species of Cyprinus, which affords so 

 many in northern Europe. This genus seems to be replaced in . 

 South America by that of the Siluri, only one of which, on 

 the other hand, exists in Europe. Thus M. d'Orbigny enu- 

 merates eighteen or. twenty species in his catalogues, very va- 

 riable in form, and consequently exemplifying many of the ge- 

 nera recently constructed. Some of them are of gigantic size, 

 measuring two or tJiree metres in length. The salmon are like- 

 wise numerous both in individuals and species, and many of 

 them are no doubt new. The same may be said of a kind of 

 mullet, of perch, lucio-perch, -and blenny, which we have seen 

 figured in his atlas. He nowhere observed any species of eel, 

 which appear to be replaced by the Synbranchiae. He speaks 

 of Clupea? and Atherinae found in the Plata, at 100 leagues 

 from its mouth ; of Plaice, in the Parana, at the distance of up- 

 wards of 150 leagues from the sea ; and of a kind of Sole, 390 

 leagues distant from the sea, on the frontiers of Paraguay. 



He observed a kind of Pastenagua, or armed fiesh-water ray, 

 and also a lamprey, in the rivers of Patagonia, but no sturgeon. 



Thus with the exception of salmon, which are pretty common 

 in the South American rivers, the ichthyological physiognomy 

 of these countries may be said to be more peculiar than that of 

 the birds. 



The molluscous articulated animals which presented them- 

 selves to M. d'Orbigny's observation, are not numerous ; the few 

 genera which constitute that subtype being all pelagic or littoral, 

 and our traveller, according to his instructions, exploring chiefly, 

 or almost exclusively, the interior of the country. 



But his investigations have been carefully directed to such of 

 the mollusca as inhabit fresh-water. Not that he has neglected 

 to observe, describe, and what is still better, to figure, tlie 

 poulpes, the seches, the calmars, and marine shells which he met 

 with in his passage from Europe to America, — from the eastern 

 side of the latter country to the western, — and finally, in his re- 

 turn to Europe. Indeed we have noticed a considerable number 

 of pteropodes, firoles, and of doris; a tancellarious animal, re- 

 markable for the absence of the respiratory tube, a fact well in- 

 dicated by the shell ; many natices, and cryptostomse, &c. But 



