96 
PALEONTOLOGY OF NEW-YORK. 
one, this interior cast often becomes the most conspicuous feature, owing to the nature of 
the material in which it is enclosed, and the conditions attending its conservation. It is evident, 
therefore, that the Genera Actinoceras and Ormoceras can not both be retained, unless 
Actikoceras 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 YIRGULATUM (n. sp.). 
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 ANNUL ATUM 1 ? 
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 
*1 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 my previous volume. 
