64. PALJ/EONTOLOGY OF NEW-YORK. 
CORALS OF THE TRENTON LIMESTONE. 
Piates XXIII. to XXVI. 
The corals of the Trenton limestone are limited to a moderate number of species, and a 
few only of these are abundant ; but one species, the CumTETES, in some of its varied forms, 
abounds in nearly all localities of the rock. These species, of which there about eighteen, 
are referable to no less than twelve distinct genera. The Chetetes Lycoperdon, in hemi- 
spheric forms, often abounds in certain layers, to the almost entire exclusion of any other 
fossil ; while the slender and branched varieties of the same species are found in other 
situations, covering the entire surface of strata for many yards in extent. These corals rarely 
attain to massive dimensions, though we sometimes meet with irregular forms weighing 
ten or twelve pounds. This species is far more abundant than any other, and, in some of 
its protean forms, is every where met with in the Trenton limestone, being much more 
numerous than all the other species together. 
During the entire deposition of this rock, the condition of the ocean does not appear to 
have been favorable to the continued growth of corals, since no massive species are found 
in it. This is probably owing to the constant intermingling of shaly matter during the time, 
which interfered with the growth of these animals; for there seems no other sufficient 
reason, since such large masses of the Cotumnaria are found in the thin layer of Black- 
river limestone below this rock. The western extension of this formation shows, during the 
same period, the existence of immense numbers of corals, none of which attain to large 
dimensions, though in their present condition they form a considerable proportion of some 
of the strata. 
101. 2. CHATETES LYCOPERDON. 
Pu. XXIII. Figs. 1, 1 a, b,c, d,e,f, g,h, 1, & 2, 2.a,3; and Pu. XXIV. Figs. 1 a, b,c, d, e, f, g,h, i,k, m,n, 0. 
Favosites Lycoperdon. Savy. 
Favosites lycopodites. VanuxEM, Geol. Report, pag. 46, fig. 3. Emmons, Geol. Report, pag. 389, fig. 3. 
Calamopora fibrosa[?] Goupruss, 1826, Petrefacta, pp. 82, 215, tab. xxvili. figs. 3&4; tab. xxiv. fig. 9. 
Favosites fibrosa? Goupruss, 1833, Petref. corrigenda, p. 245. 
Compare Chetetes petropolitanus, LonspaLe; Favosites petropolitana, PANDER. Murcuison & VERNEUIL, 
Geology of Russia and the Ural Mountains, pag. 596, pl. A. fig. 10. 
Coral polymorphous, composed of closely aggregated tubes or columns, which diverge 
gradually from a broad base forming hemispherical masses, or from an imaginary axis 
producing conical or ramose forms; tubes minute, fibre-like, traversed by diaphragms ; 
no connecting pores ; increase of the coral by subdivisions of the parent tube, or by the 
successive addition of lateral or marginal tubes ; exterior envelope submembranous. 
This abundant coral appears in hemispherical, conical, nearly globular and ramose forms. 
Its most usual form is the hemispheric or puffball-shape, from which it received its name 
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