10 
PALEONTOLOGY OF NEW YORK. 
The forms described as T. temistriatus, T. Oswegoensis, T. Sterlingensis* and T. 
Richm,ondensis,\ are rarely if ever quite straight, and are usually considerably 
curved, a feature unknown among the most characteristic forms of the genus 
Tentaculites. The T. incurvus of Shumard, now recognized as from the same 
horizon, is a curved form, as the name implies. We have at the outset, there¬ 
fore, in all these species, to recognize a deviation from the acknowledged char¬ 
acteristics of Tentaculites as described by the best authors and as known to us 
in American and European rocks. These forms in their intermediate stages 
are sharply annulated, and, in their advanced stage of growth, always longitu¬ 
dinally striated in a manner not observed among true Tentaculites. Farther 
observation shows that in their young state they are parasitic, often occurring 
in groups, with their bases in contact and attached to some foreign body, as a 
shell or a fragment of a crinoid column; and that the extreme basal portion or 
initial point, in the young state, is always curved, often to a full volution; but 
this portion becomes absorbed, dissolved or worn off as the animal increases in 
size and the .tube assumes a more or less direct manner of growth, continuing in 
a straight or slightly Ilexuous line and gradually enlarging toward the aperture. 
These tubes which in their beginning are apparently smooth, gradually become 
annulated and finally striated longitudinally. It usually and perhaps always 
happens, however, that during some stage of their growth, not always depend¬ 
ing on the age, the walls become thickened and the annulations obsolescent. 
Occurring either singly or in groups, wherever the surface of attachment is broad 
enough to admit of it, they continue adherent until they have attained a con¬ 
siderable size—that is, a length of 20 to 35 mm., or even more. The apertures 
in nearly all examples are apparently incomplete, or with the margins broken. 
The phases here described are illustrated in figures 1-11 of plate cxv. 
Under other circumstances, where apparently the conditions have been un¬ 
usually favorable, these colonies, adherent to some other body at their bases 
only, continue to increase in length and diameter; the lateral walls from being 
simply in contact become coalescent, and they continue this growth till the form 
* See Proceedings of the Academy of Sciences, Philadelphia, and Report Geological Survey of Illinois, 
vol. iii. 
t S. A. Miller, Gin. Quart. Jour. Sci. 1874. 
