33 



race, in many places, small springs of water constantly flow, falling 

 only in drops. Beneath is the incoherent quartzose sand of a ferru- 

 ginous colour, which contains myriads of perfect but friable shells, 

 of which there are about seventy genera and rather more than two* 

 hundred species. Those bivalves which have' a strong ligament or 

 cartilage, as the Lucincn and the larger Crasaatellie, generally have 

 their valves in apposition and the cartilage still occasionally remains. 

 The Cytherea suberycinoides, (Desh.) the most abundant fossil at 

 Claiborne, very seldom has the valves in connexion, but if there has 

 been any disturbance at the time of deposition, it has not been 

 sufficient to injure the most delicate angles and striae of the 

 shells. Occasionally specimens are found which still retain their 

 coloured markings. The surface of this stratum, where a portion 

 of the sand has been washed away by the lains, presents the aspect 

 of a solid bed of shells. Near the base of it, whatever point was 

 examined, a vein of very soft lignite was observed, and what is 

 remarkable, certain fine large univalves appear almost exclusively 

 confined to this lignite, as if it had been formed from vegetable sub- 

 stance in the Eocene ocean to which those univalves were partial. 

 Beneath this line, the sand is somewhat coherent, and many species 

 of shells are more abundant whilst others are more rare than above 

 it. 



In the introduction to this work, I gave the first notice of this 

 interesting locality, and referred -it to the period of the London clay 

 and Calcaire grossicr, giving it a provisional name which I gladly 

 abandon since a better has been supplied in the Eocene of Professor 

 Lyell. That it is of the same, or nearly the same age, I think the 

 organic remains, described in the following pages, will incontestably 

 prove. Whether any of the species, except Cytherea erycinoi- 

 des, does exist or not in the present ocean, I cannot pretend to de- 

 cide, as our cabinets are too imperfect to admit of certainty in this 

 point, but I am unable to refer any to such recent species as have 

 come under my observation. None, it appears from comparison, 

 inhabits the coast of the United States, and what is more remarkable, 

 but two have been found in the Pliocene of our country. There is 

 therefore a more marked distinction between the two tertiary forma- 

 tions than between the Eocene and Cretaceous strata, because four 

 species of fossils are common to the two Blatter, facts just the 

 reverse of those which have been published in relation to the second- 

 ary and tertiary of Europe. No vestiges of fresh water shells are 

 observed in our Eocene, and I conclude, from the general character 

 of the fossils, that the formation, unlike that of Paris, has not been of 



1 89] 



