GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 301 



in shape, and surrounded by a strong and thickened wall, the 

 intervals between them being occupied by the smaller tubes. 

 The large corallites are traversed by a few remote tabulae, 

 and the small tubes are closely tabulate, their tabulae often be- 

 coming subvesicular, while their walls become obsolete. The 

 above characters will be more fully brought out by a brief 

 description of the type-species, the Constellaria antheloidea, 

 Hall, of the Lower Silurian of America. 



Constellaria antheloidea, Hall. 

 (PI. XIV, figs. 5, S J.) 



Stellipora antheloidea, Hall, Pal. N.Y., vol. i. p. 79, PI. XXVI., figs. 10 a, 



10 c, 1847. 



antheloidea, D'Orbigny, Prodr. de Paleont, t. i. p. 22, 1850. 



Constellaria antheloidea, Edwards and Haime, Pol. Foss. des Terr. Pal., 



p. 279, PI. XX., figs. 7 - 7 b, 1851. 



antheloidea, Nicholson, Pal. of Ohio, vol. ii. p. 214, 1875. 



,, antheloidea, Nicholson, Ann. Nat. Hist., ser. 4, vol. xviii. p. 92, 



PL V., fig. 10, 1876. 



Spec. G&tfr. Corallum in the form of palmate, or sublobate, 

 flattened expansions, two or more inches in height, with a thick- 

 ness of from one and a half to two lines, and .composed of 

 corallites which radiate from an imaginary central plane to 

 open on all unattached parts of the skeleton. Surface (PI. 

 XIV., fig. 5) with numerous stellate areas, a line or less in 

 diameter, and placed about half a line or rather more apart, 

 each consisting of a depressed central space, surrounded by 

 from six to eight prominent and radiately - placed elevated 

 ridges. Corallites of two kinds, large and small. Large coral- 

 lites oval or circular, about one-tenth of a line in diameter, with 

 strong bounding-walls, occupying the general surface of the 

 corallum, and specially aggregated on the elevated ridges of 

 the star-shaped monticules, in the central depressed areas of 

 which they are wanting. Small tubes, apparently really sub- 

 angular, occupying all the interspaces between the larger oval 



