208 
PALAEONTOLOGY OF NEW-YOltK. 
siphuncle, more approximate than the annulations ; siphuncle large, subdorsal, containing 
a smooth embryo tube ; section circular. 
A fragment of this species, two feet in length, is all that I have seen, though the original 
must have been at least three times this length. This is the largest of the annulated species, 
and is clearly different from all the others in the rock, which have small siphons, and are 
of far smaller size, with more abruptly elevated annulations. The annulations in this species 
are broadly arched on the dorsal side, which is at the left hand of fig. 1 a. The septa are 
direct and plainly arched, being distant about three fourths as far as the annulations. The 
internal tube, within the siphon, is not annulated. There is also, apparently, the apex of 
another tube within this one, which is not central; but this appearance may be due to 
accidental displacement. 
Fig. 1 a. Lateral view of a fragment, showing the arching of the annulations towards the left side. 
The fine dark transverse lines indicate the edges of the septa. 
Fig. 1 b. Longitudinal section of the last, showing the position of the siphuncle, convexity of the septa, 
and internal tubes. 
Position and, locality. This species occurs in the compact lower strata of the Trenton 
limestone at Watertown. (From Dr. Crawe.) 
ENDOCERAS PROTEIFORME (n. sp.) 
Plates XLV. to L., & LIII. 
General form cylindrico-conical, more or less elongated, often compressed, tapering 
somewhat unequally in different specimens ; young specimens terminating in an extremely 
acute point; surface marked by distinct transverse striae, which usually appear like narrow 
subimbricating bands, with one edge well defined and more elevated than the other, more 
or less distinctly striated longitudinally ; striae varying from extreme tenuity to distinct 
elevated threadlike lines ; section circular ; septa distant from one fifth to one fourth the 
diameter ; siphuncle excentric or submarginal.* 
I am able to characterize three distinct varieties of this species, which are the prevailing 
forms : these depend mainly on the surface markings of the young shell. The old shells are 
recognized by a large submarginal siphuncle, which usually contains a smooth cylindrico- 
conical embryo tube or sheath. This tube is sometimes irregularly tapering, and always 
free from visible surface markings or sculpture. Within this embryo tube are the young 
shells, sometimes perfectly formed Orthocerata, and at other times destitute of septa or 
* This is a very variable species, which, in its extreme varieties, I have been disposed to regard as specifically 
distinct. The engravings of the two first plates (xlv and xlvi) were made with this view; and the parent shell, with 
the smooth embryo tubes figured on the subsequent plates, was considered distinct, presenting no characters which 
could be identified as common with those figured on Plate xlv. It is only by some fortunate discoveries made since the 
engraving was completed, and while my descriptions are passing through the press, that I am able to present the true 
characters of this protean species. The two plates xlv and xlvi were figured during the early part of the preparation 
of this work in 1843, and my subsequent investigations have furnished the other specimens which appear on the 
following plates. This will account for the want of unity or completeness in the grouping of the different varieties. 
