PALEONTOLOGY OF KEW-YORK. 



one, this interior cast often becomes the most conspicuous feature, ov/ing to the nature of 

 the material in which it is enclosed, and the conditions attending its conservation. It is evident, 

 therefore, that the Genera Actinocekas and OaMOCERAS can not both be retained, unless 

 AcTiNocERAS Can be shown to relate to some other fossil than that to which it was originally 

 applied. It is true this name has priority over Ormoceras, but being founded in an erroneous 

 opinion of a fossil drawn from a figure, I have preferred to retain the latter name ; since 

 it is founded on a character belonging to the fossil, and not to a peculiarity exhibited in the 

 cast*. 



Position and locality. All the specimens of this species known to me have been collected 

 near Reynale's basin, Niagara county, from the lower part of the group. [State Collection.) 



491. 28. ORTHOCERAS VIRGULATUM (7t. 5p.). 



PL. XXIX. Fig. 2 a, b, c. 



Slender, cylindrical, gradually tapering ; siphuncle sub-central ; surface marked by small 

 round pits or punctures. 



The subtance of the fossil is converted into a kind of chalcedony, and the shell is silicified. 

 The punctures on the surface are probably not original markings of the shell, but due to 

 weathering and the peculiar arrangement of the siliceous particles. In another specimen, these 

 puncta are not preserved. 



Fig. 2 a. A small fragment preserving the shell. 



Fig. 2 b, A section of the last. 



Fig. 2 c. A silicified fragment broken through the centre longitudinally, except the lower part. 



The greater convexity of the septum shown in this figure, over that in fig. 2 a, is 



owing to lateral pressure. 



Position and locality. In the lower siliceous limestone of the group, associated with the 

 preceding species, at Reynale's basin, and also at Lockport, Niagara county. 



492. 29. ORTHOCERAS ANNULATUM ? 



PL. XXIX. Fig. 3. 



Reference, Orthoceras annulatum, Sowerby, Min. Conchology, t. 133. See description, etc. 



under Orthocerata of the Niagara group. 



The fragment figured does not appear separable, by any specific distinction, from the species 

 in the Niagara group which is illustrated on Plate 64. It is much compressed, so that the 



* I should not omit to state here that I have this moment had an opportunity of seeing Mr. M'Coy's observations 

 on the same subject, in his Synopsis of the Carboniferous Fossils of Ireland, which work was unknown to me except 

 by name when I published niy previous volume. 



