122 
PALAEONTOLOGY OF NEW-YORK. 
512. 2. ASTROCERIUM PARASITICUM. 
Pl. XXXIY. 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 ones 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 b. 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 j 
e and e-f-, where the stem of a Caryocrinns 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, which enclosed a fragment of an ichthyodorulite. 
Fig. 2/. 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 g. 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 thHirnestone near Lorkport. 
