122 



PALEONTOLOGY OF NEW-YOEK. 



512. 2. ASTROCERIUM PARASITICUM. 



Pl. XXXIV. Fig. 2 a-i. 



Corallum hemispheric, spheroidal, growing independently, or attaching itself and growing 

 upon, or enveloping other bodies ; composed of angular tubes or cells ; openings of cells upon 

 the surface unequal in size, stellate, with twelve to twenty-four spiniform rays ; tubes trans- 

 versely septate. 



This species has the general appearance of Favosites, from which it is often almost impos- 

 sible to distinguish it. The coral increases by lateral and interstitial addition of cells, the 

 younger oiies being more angular and smaller than the older ones. In many specimens the 

 mass is solid, and separable into columns as in Favosites ; while the stellate character is still 

 preserved in the ends of the tubes. In other specimens, where the cells are open, the spiniform 

 rays have often been destroyed, and the specimen has all the appearance of a true Favosite. 

 The utmost care is required, therefore, in discriminating the species. It should be observed, 

 that in tubes destitute of the rays, the sides are marked by little processes which are the 

 bases of the rays, giving the whole interior surface a papillose appearance. Where the coral 

 IS silicified, however, this character fails, and the walls of the cell present only an aggregation 

 of small siliceous concretions. 



This species, in the young state, attaches itself to shells, to stems of living crinoids, and to 

 other corals, being eminently parasitic in its habit. 



Fig. 2 a A small spheroidal form, attached to a coral which projects beyond the base. 



Fig. 2 h. A small spheroidal specimen. 



Fig. 2 c. A spheroidal mass with the cells open on a part of the surface, showing the unequal size 



of the openings ; the interspaces are also very wide. 

 Fig. 2 d. A smaller mass enclosing a piece of a crinoidal column, which projects on both sides 



of the coral ; and it is probable, from the habit of this species, that it commenced 



growth on the crinoid while the latter was in a living state. See Plate 49 a, fig- 1^ 



e and e-{-, where the stem of a Carvocrinns is enveloped in a similar manner by a coral 



of this species. 



In this and the preceding specimen the cells are open on the surface, and distinctly 



stellate. 

 Fig. 2 e. Section of a spherical mass, wllich enclosed a fragment of an ichthyodorulite. 

 Fig. 2 f. A portion of the surface from a large specimen, where the cells are filled, and the whole 



mass is columnar. The ends of the columns present a confused stellate character. 

 Fig. 2 ^. A small portion from the base of the last, showing the weathered surface of the 



columns. 

 Fig. 2 h. The ends of the tubes enlarged, showing the stellate character. 

 Fig. 2 i. Figure showing the papillose surface of the interior of the tube when the rays are 



broken away, leaving the bases projecting. 



Position and locality. In the lower part of the limestone near Lockport. 



