PRELIMINARY REMARKS. 



In oflfering the following report on a portion of the organic remains of 

 New Jersey, I would state that the very imperfect material with which I 

 have had to deal, as well as the small number of related specimens, often 

 having only a single imperfect individual of a species, and that one the 

 original type, must form my excuse for the great imperfection of descrip- 

 tion and meagreness of illustration. 



The report contains all the species oi BracUopoda and LameUibranchiata 

 of the greensand marls and their accompanying clays of the State, so far as I 

 am able to learn, hitherto described and pubHshed, as well as several now 

 made known for the first time. The published species have not before been 

 brought together in any form, even in a catalogue; and the descriptions 

 have been given in so many different publications, and through such various 

 channels, that it has been very difficult to ascertain when they had all been 

 collected. I am by no means certain, even now, that I may not have over- 

 looked some isolated paper or obscure pamphlet containing descriptions or 

 mention, but everj' means has been employed to make the search as thorough 

 as possible, and every known trace of publication or reference to papers 

 has been followed to its source. 



Another difficulty with which I, have had to contend has been the want 

 of material. This has been an almost insurmountable obstacle to rapid and 

 systematic work, as there are no comparatively complete collections of the 

 marl fossils in existence at any one place. This arises principally, I pre- 

 sume, from the fact that marl fossils are very difficult to preserve for any 

 length of time, owing to their rapid disintegration from the effects of finely 

 disseminated pyrite in the marls, which, on exposure to the air, rapidly de- 



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