8 SYNOPSIS OF 



ment furthest removed from the observer, and the beak to the 

 rio-ht of it. The base will of course be nearest to him, and 

 the anterior margin to his right, while the posterior margin 

 will be to the left. This is my mode of arranging my whole 

 cabinet. 



In attempting to make a complete synopsis of the Naiades, 

 much labour has necessarily been bestowed upon it. I do 

 not present this as a perfect work, but as much so as I could 

 with the opportunities in my possession make it. Errors 

 may have arisen from two sources : first, default of judgment ; 

 second, accidental, owing to the mass of research necessary 

 to accomplish the object, considering the crude state the sub- 

 ject was in. I shall be most agreeably disappointed if there 

 be not parts pointed out as erroneous which are substantially 

 correct. It will be observed that the works of M. Rafinesque 

 are but little quoted. This has arisen from the utter impossi- 

 bility of satisfying myself as to his species. The cause of 

 which was, at an early period, the abandonment of pursuing 

 the impracticable task of making them out. His own dis- 

 crepancy in the names sent to Ferussac,* and those which 

 are attached to specimens here, together with the want of 

 accordance in the tables made out by his friends, have induced 

 me to regard his claims as being too slender to rely upon the 

 decisions, so contradictory of the several parties, in the ab- 



* " Les erreurs involuntaires qui echappent a M. Rafinesque dans ses en- 

 vois augmentent aussi la difficulte de reconnaitre ses especes. Nous avons 

 reju de lui les menies coquilles sous differents noms, et d'autres avec les 

 noms evidemment autres que ceux qu'elles portent dans sa Monographie. II 

 en est resulte une difficulte inextricable pour la determination de ses especes, 

 et pour pouvoir etablir une synonymie exacte entre lui et les autres qui, de- 

 puis, se sont occupes des Mulettes." — Observations, p. 13. 



