CORALS OF THE CLINTON FORMATION. 227 



Halysites catenulaeia, Linnaeus. 



Tubipom catermlaria, Linn6 ; Syst. Nat. Ed. Xll., p. 1270, 1767. 



Ciitenipora labyrinthica, Goldfuss; Petref. Germ., Vol. I., p. 75, pi. 25, flg. 5. 



Catenipora escharoides, DeBlainville ; Man., pi. 65, flg. 5. 



Catetdpora escharoides, Hall ; Pal. N. Y., Vol. II., pp. 44 and 127, pi. 18, fig. 2, and pi. 



35, flg. 1. 

 Halysites catenularia, Edwards and Haime; Pol. Foss. des Terr. Palaeoz., p. 281. 

 Halysites catenularia, Edwards and Haime; Brit. Foss. Corals, pi. 64, figs. 1, Ic. 



It does not seem necessary to give either a description or a full syn- 

 onymy of this very common and well known coral. It is most readily 

 recognized by the loosely reticulated corallum, composed of interlacing 

 vertical plates, each of which in turn is made up of tabular corallites. 

 The tabulae are well developed, and the existence of septa can often be 

 determined without difficulty. The size of the meshes of the corallum 

 varies very much, though not so much as the size of the individual 

 corallites. The calices are elliptical in shape, and their long diameter 

 may vary from as little as one-third of a line to as much as one line and 

 three-quarters, or more than five times as great. Nevertheless, the 

 gradations between the smallest and largest forms are so numerous that 

 it is impossible to believe that we are dealing with more than a single 

 species. , Milne Edwards and Haime, with more or less doubt, retain the 

 name of Halysites escharoides for those forms in which the reticulations of 

 the corallum are small, polygonal, and of nearly equal dimensions. I 

 think it very doubtful if this form can be regarded as more than a mere 

 variety of H. catenularia; but it appears to me, from the specimens 

 which I have examined, that H. agglomerata, Hall, may fairly be consid- 

 ered as distinct. 



Position and locality : Clinton group, Preble county, Ohio. 



AcERVULAEiA Clintonensis, Nicholson. 



Plate 23, figs. 2, 2a. 



Corallum astrffiiform, plane composed of polygonal corallites closely 

 united with one another. The outer walls of the corallites very thick, 

 either slightly undulated or straight. The corallites are somewhat un- 

 equal in size, and usually pentagonal in shape, their great diagonal vary- 

 ing from three to six lines, but averaging about four lines. The inner wall 

 is extremely well marked, sometimes slightly elevated above the bottom of 



