410 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
Monilopora Nich. and Eth. Jr. 
Geol. mag., 1879, vol. 6, p. 293. 
Description. Corallum compound, increasing by lateral gemma¬ 
tion ; commonly attached to foreign objects of support. Septa 
absent or represented by faint marginal striae or Ratings on the 
interior of the calices. Visceral chamber of corallites open and free 
from tabulae. Wall extremely thick, exhibiting in section, for the 
most part, a distinctly fibrillated appearance, from being composed 
of successive concentric layers. Concentric lamellae of the wall 
frequently separated, so as to include a series of distinct interspaces 
or lacunae, which are approximately parallel to the axis of the vis¬ 
ceral chamber, and which are crossed at right angles by numerous 
delicate cross-bars or trabeculae of sclerenchyma, forming a reticu¬ 
late structure. 
The characteristic features of this genus are: the open central 
cavity, free from tabulae; the concentric lamellae of the wall; 
and the reticulate structure, which in the type species “ * * * seems 
to be sometimes partially developed in the basal portions of the 
corallum, but is essentially and principally, if not altogether, present 
in that portion of the wall which forms the actual cup of each cor- 
allite.” (Nich. and Eth. Jr., loc. cit. p. 295.) 
Type. Monilopora crassa (M’Coy). 
Range and distribution. This genus has been found in the 
lower Carbonian rocks of Europe and North America, and recently 
in the middle Devonian of North America. 
Monilopora crassa (M’Coy). 
Jania crassa M’Coy, Synops. Carb. limestone foss. Ireland, 1844, 
p. 197, pi. 27, fig. 4. 
Cladochonus (Jania) crassus M’Coy, Ann. and mag. nat. hist., 
1847, ser. 1, vol. 20, p. 227. 
Cladochonus crassus M’Coy, Ann. and mag. nat. hist., 1849, ser. 
2, vol. 3, p. 134. (Listed.) 
Cladochonus crassus M’Coy, British Palaeozoic fossils, 1851, p. 
85. 
Cladochonus crassus Morris, Cat. British fossils, 1854, ed. 2, p. 
49. 
