4 Synopsis of the Fresh Water Fishes 



II. 



In tlie first collection of fliiviatile fishes whicli we had the 

 privilege of examining, there were fonnd to be species of the 

 genus Hypostomus of Lacepede and of the Callichthys of 

 Linnsens, — one whicli represented the naked Siluroids and 

 belonged to one of the South American types of the extensive 

 genus Pimelodus, as it has been adopted by Valenciennes in the 

 " Histoire ISTaturelle des Poissons," and finally, a species of the 

 family of Cyprinodonts of Agassiz. The first three are mem- 

 bers of groups nearly peculiar to South America. It was conse- 

 quently discovered at an early period of our investigations, that 

 the resemblance which existed between the mammalian and orni- 

 thic faunae of the island extended also to the fishes of its rivers. 

 Believing that these facts would be interesting contributions to 

 the knowledge of the geographical distribution of animals, and 

 having many new species and genera which we were desirous 

 to make known, we have prepared the present synopsis. 



It is not our intention in this communication to discuss the 

 geographical distribution of fishes of the island. We defer 

 this to a future time. At present, we will only remark that we 

 are not acquainted with a single genus of fishes inhabiting the 

 island and peculiar to the fresh waters, that is common to the 

 United States, or indeed, as far as is yet known, to any portion 

 of Korth America. 



III. 



In the memoir which we now offer as a contribution to the 

 history of the fresh water fishes of the island of Trinidad, it 

 is designed to give detailed descriptions of the genera, and such 

 concise, comparative descriptions of the species belonging to 

 them, as will enable naturalists to distinguish them from all the 

 other species of the groups now known. At a future time the 

 various new species which are here indicated will be described 



