of 305 Genera appear, arranged in their proper order. Upwards of 500 American 

 species will be found distributed among the diflerent Genera, with references to Ame- 

 rican works, where they are figured or described. Indexes are annexed, containing the full 

 titles of all the works referred to, and the names of the authors of species, which are 

 generall}'' abbreviated. 



With regard to the shells figured in the Plates, my object is to obtain information 

 respecting them, whether they are new or not, and I will therefore be happy to receive any 

 information respecting them ; only observing, that, in the event of any of them proving 

 new, a further description of them will appear in the Annals of the Lyceum of Natural His- 

 tory of this City. I have been disappointed in the execution and coloring of the Plates, 

 particularly in the figures of Conus Rhododendron, Couthouy, and Dohum Melanostomum, 

 Nobis, which fall far short of exhibiting their beauty and brilliancy. 



Plate I. of the last edition, containing well-known shells, as it would appear, has not 

 been inserted ; but for the information of those of my friends who may not be aware of the 

 fact, I would state that Figure 1 is Bulimus pentagruelina, Moricand. Figure 2 is Pupa 

 elatior, Spix. Figure 3 is Bulimus melanostomus, Swainson. Figure 4 is the young shell 

 of Bulimus bilabiatus, Sowerby, published in the Zoological Journal, vol. v. p. 49, and 

 afterwards, Bulimus maximilianus, by Moricand. 



In the Malacological and Conchological Magazine, Part 1st, for a copy of which I am 

 indebted to the Author, Mr. G. B. Sowerby, that gentleman remarks, that Aplysia is more 

 proper than Laplysia ; and also desires to know the author of the Genus Dijthalmia. My 

 Catalogue was too far advanced to make the desired alteration, or to insert the above 

 authority. I have since learned, that M. MiJhlfield is the author of Dijthalmia Danubii, 

 and am disposed to think it a different species from the Mytilus polymorphus, Gmel. 



Collectors are not probably aware that the Numbers, in the first column, are, and always 

 will be constant : so that by placing the same Numbers on their specimens, and making a 

 slight mark opposite the corresponding number in the Catalogue, they will have a Catalogue 

 of their own collection, with very little trouble ; and, by having it interleaved, can insert any 

 others, in their proper places. 



With respect to exchanges, I repeat, that it will give me pleasure to exchange duplicate 

 specimens, and will receive live and perfect shells, whether they are enumerated in this 

 Catalogue or not ; and, as far as I am able, supply whatever may be desired in return. 



JOHN C. JAY, 22 Bond-street. 



New-York, April, 18.39. 



