48 PERMIAN FOSSILS. 



it may be said that in Acanthocladia the gemmuhferous vesicles are prominent, and 

 situated on ridges which separate the rows of cellules ; whereas in Thamnisciis they are 

 cup-shaped cavities overlying the cellule-apertures. 



Mr. M'Coy's genus Ichthi/orachis appears to be closely related to Acanthocladia in 

 Its mode of branching ; but the arrangement of the cellule-apertures favours the idea 

 of its reproductive character being similar to that of TJiamniscus. 



All the known species of Acanthocladia are confined to the Palaeozoic formations. 



Acanthocladia anceps, Schlotheim. Plate V, figs. 13, 14, 15, 16, 17, 18. 



Keratophytes anceps, Schl. Miinch. Akad., vol. vi, p. 20, pi. ii, fig. 7, 1820. 



— — „ Petrefacten, p. 341, 1820. 



Ceuatophyllites — Schl. Boue, Edin. Phil. Journ., vol. xii, p. 144, 1825. 

 GoBGONiA — „ Goldfuss, Petref., p. 98, pi. xxxvi, fig. 1 a, h, c, d, 



1828. (?) 

 An unknown Coual, Sedgwick. Trans. Geol. Soc. Lond., 2d series, vol. iii, pi. xii, 



fig. 7, 1829. 

 GoRGONiA ANCEPS, ScM. Germ. Transl. Geol. Man., p. 459, 1832; and 3d Eng. ed., 



p. 572, 1833. 



— — „ Phillips, Encyc. Met., vol. vi, p. 615, 1834. 



— — „ Geinitz, Neues Jahrbuch, p. 541, 1841. 



— — ET G. DUBiA, Schl. Morris, Catalogue, p. 38, 1843. 



— — „ Geinitz, Gsea von Sachsen, p. 98, 1843. 

 Fenestella — „ Bull. Soc. Geol. France, 2°"= ser., vol.i, p. 24, 1844. 



— — „ Geol. Russia, vol. i, p. 221, 1845. 



— — „ Tennant, Strat. List Brit. Foss., p. 88, 1847. 

 Ceratophytes — „ King, Catalogue, p. 6, 1848. 

 Fenestella — „ Howse, T. N. F. C, vol. i, p. 261, 1848. 



— — ET G. DUBTA, Schl. Geinitz, Verstein., p. 18, pi. vii, figs. 19, 20.. 22, 



1848. 



Diagnosis. — Stems numerous, erect, frequently dividing pinnately. Pinnules 

 slightly tapering, generally opposite to each other, and blunted at their extremity. 

 Rows of cellules from three to six on the stems. Cellule-apertures more or less circular, 

 and somewhat apart. Capillar^/ tubes slightly flexuous.^ 



This Coral consists of a number of long, slender stems, rising from a small base 

 round an imaginary axis, and giving off bilaterally, and at regular distances from each 

 other, numerous branches, generally short and simple, but occasionally elongated, also 

 bilaterally branched, and sometimes still further developed in the same way, assuming, 

 hi short, a bi- and even a tri-pinnated form. The rows of cellules, separated from each 

 other by a slightly-developed dividing ridge, are variable in number : generally there 

 are only three ; but in some specimens so many as six may be counted. The vertical 



' The following is Goldfuss's diagnosis : " Gorgonia ramosissima, ramis subdichotomis, ramulis distichis 

 brevibus, cortice osculis papulosis serialibus costata." (Petrefacta Germanise, vol. i, p. 98.) 



