12 
PALEONTOLOGY OF NEW YORK. 
a specimen with abnormally thickened walls and great development of vesicu¬ 
lar tissue. 
With all the material here illustrated on plate cxv, and much more before 
me, I am unable to find any characters by which generic or specific distinction 
can be drawn between the forms represented in figures 1 and 2 and all those 
which follow up to figure 39. The names under which these and similar forms, 
as before mentioned, have been described are: Spirorbis Cincimatensis, Tentacu- 
lites incurvus, T. tenuistriatus, T. Oswegoensis, T. Sterhngensis and T. Richmondensis. 
Besides the species above enumerated, these organisms, in their different 
phases of development, have furnished the basis for the establishment of the 
genus Ortonia (0. minor and 0. conica), and a species described under Conchico- 
LiTES {C. corrugatus). The latter genus was founded upon a similar organism, 
occurring in the Caradoc shales of Westmoreland, England, the equivalent, in 
age, of the Hudson Biver group of America (American Journal of Science, 
Third Series, vol. iii, p. 202. 1872). 
The manner of growth and development; the external form and internal 
structure of these bodies, seem to demonstrate very clearly that they should be all 
referred to the genus Cornulites, as described and illustrated by the author of 
the genus and by subsequent authors whose opinions are entitled to respect. 
The description and illustrations of Cornulites sei'pularius, Murchison (Silurian 
System, p. 627, and plate xxvi, figures 5-9), present a most important study in 
this connection, and leave no doubt as to the nature of the organism under 
consideration. 
In regard to the forms illustrated on plate cxv, figures 1-39,1 do not propose 
to recognize any distinction of species, and I leave them without prejudice to be 
referred to such specific names as their authors may claim for the various phases 
here represented. Though referring certain of the illustrations to the names 
by which they are usually recognized, I have purposely confined myself to the 
discussion of the various phases of what appears to me a single form of this re¬ 
markable organism, all the specimens being from the same geological horizon. 
Figure 40 represents the earlier stages of an irregular group growing upon 
the shell of an Orthoceras, from the Utica slate of New York, and which pre- 
