76 PALJEONTOLOOY OF NEW-YORK. 



115. 2. GORGONIA PERANTIQUA. 



Pl, XXVI. Figs. 5 a, b. 



Coral consisting of niunerous small branches proceeding from a central point ; branches 

 bifurcating, smooth, or very finely striated ; cellules arranged on two sides of the axis, 

 opening laterally. 



The specimen consists of a number of lax branches, apparently diverging from a centre 

 or point of attachment : these branches are several times subdivided, but present no evidence 

 of connecting bars. 



The species is exceedingly rare, a single one being all that has fallen under my notice. 



Fig. 5 a. The specimen, natural size. 



Fig. 5 & A portion of a branch enlarged, showing the openings upon the two sides of the axis. 



Position and locality. In the soft shaly layers of the lower part of the Trenton limestone, 

 near MiddUville, Herkimer county. 



116. 1. AULOPORA ARACHNOIDEA. 



Pl. XXVI. Figs. 6 a, b, e. 



Coral consisting of a fine weblike expansion, diffusely branching and anastomosing, 

 attached to the surface of other bodies ; tubes narrow, slender, short, subclavate or straight, 

 single ; mouth sliglitly elevated, opening obliquely upwards, smaller than the cell below. 



This very delicate species, in some portions of its extent, bears considerable resemblance 

 to Alecto dichotoma of the Jura limestone ( Lamoukoux, Exp., p. 84, t. 81, f. 12 - 14 ; 

 Blainville, Man. d ^Ad., p. 464, t. 65, f. 1 ; Aulopora dichotoma, Goldfuss, Petrefacta, 

 pag. 218, pl. 65, fig. 2); but other portions develop a structure scarcely compatible with 

 this genus, and I have therefore placed it imder the Genus Aulopora. The illustration 

 below presents a magnified view of a distinct part from that shown on the plate, and 

 exhibits the essential characters of Aulopoe.*.* It is the only species of the genus known 



* A magnified portion of this fossil, a part of which (a) shows the character of Aulopoka, while other portions 

 (b) more nearly resemble Alecto. 



