14:3 PROCEEDINGS OF THE ACADEMY OF 



r 

 from the typical forms of that group, in having a perforated umbilicus ; while 

 their whorls are less compressed laterally, more slender, and provided with seve- 

 ral distinct revolving angles and grooves. They also differ in being often or- 

 namented with well defined longitudinal lines. 



This group appears to be mainly, if not exclusively, confined to the Car- 

 boniferous system, and will include in addition to our N. digonus and N. tri- 

 sulcatus, the following foreign species : Nautilus stigalis, N. Edwardsianus, and 

 N. Omalianus of Koninck, together with N. sulcatus, N. pinguis and N. carini- 

 formis of Sowerby. 



We believe all such fossil shells will some time be separated entirely from 

 the genus Nautilus. 



Note. Our recent investigations enable us to make the following corrections 

 in regard to a few of the fossils described in our papers of September and Octo- 

 ber, 1860 : 



1. Cyathocrinus scitulus (Sept. 1860). In comparing this species with those 

 described by Prof. Hall, in the supplement to the Iowa Report, we overlooked 

 its probable identity with his C. sculptilus. The fact that he had described 

 the first anal plate of C. sculptilus as being "nearly as large as the subradials 

 [and] heptagonal " in form, led us to regard our crinoid as a distinct species, 

 and it was not until our description was in print, that a more careful exami- 

 nation of his diagram on page 60, satisfied us that he had inadvertently de- 

 scribed one of the subradial plates as the first anal piece. When this correc- 

 tion is made in his description, it agrees so nearly with our crinoid, that we 

 have scarcely a doubt in regard to its identity with his species ; and as his 

 name was first published, it will have to take precedence. 



2. Platyostoma nana, (Oct. 1860). Better specimens show this to be a true 

 Naticopsis. 



3. Eulima peracuta, (Oct. 1860), should be ranged under Polyphemopsis, of 

 Portlock, probably a section of the genus Loxonema. 



4. Orthoceras expansum, (Oct. 1860), belongs to the genus or subgenus Ac- 

 tin oceras. 



5. Cyrtoceras curtum, (Oct. 1860), should be ranged under the subgenus 

 Aploceras. 



Descriptions of New Fossil Mollusca, from the Cretaceous Formation at Had- 

 donfield, New Jersey. 



BY ISAAC LEA. 



In December, 1858, I published, in connection with Prof. Leidy and W. Par- 

 ker Foulke, Esq., in the Proceedings of the Academy, some account of the 

 Green Sand Formation at Haddonfield, New Jersey. I then gave reasons for 

 believing that this interesting and extensive deposit which my late learned 

 friend, Professor Vanuxem, was the first to place on its true horizon, in relation 

 to the well known Cretaceous deposits of Europe might be the analogue of the 

 u Etage Cenomanien " of D'Orbigny. The object being, then, simply to make 

 out some of its relations, its extent so far as known, and its true position in 

 relation to our Cretaceous Formation, I gave only a list of genera of the Mollusca, 

 found by Mr. Foulke and myself. I now give a complete list of all the species 

 we then discovered, and I add descriptions of the few species which had not 

 heretofore been observed. It will at once be recognized by those who have 

 studied the Cretaceous masses of the United States, that there is a very strong 

 similarity, if not identity, of this deposit at Haddonfield, with that of the 

 " Ripley Group " in Mississippi, from which Mr. Conrad and Mr. Gabb have 



[June, 



