216 R. F. Tomes—On Heterastreea, Lower Lias. 
specimens are fully in accord with the fragment figured by M. de 
Fromentel, excepting that in addition to fissiparity there is undoubted 
marginal gemmation, which is, however, unfrequent, not more than 
three or four instances appearing on either specimen. 
Hursrastr#A Erurripgst, sp. nov. Pl. VII. Figs. 1, 2. 
This species, which appears to be undescribed, bears a little resem- 
blance in the form of the corallum to H. Haimei, but it differs greatly 
in the size of the calices, which are scarcely half the size of those 
of the last-named species. 
The corallum is tall and somewhat compressed, swith a rounded 
top, the whole surface being closely covered with calices, which are 
hexagonal, shallow, and saucer-shaped. The walls are thick, but 
when entire come to a sharp well-defined edge, and there is a very 
distinct though fine line where the corallites come together, indicat- 
ing imperfect union. 
No cyclical numeration of the septa can be formulated. There 
are about twenty-four in a medium-sized and regular calice, and 
nearly half of them pass almost into the centre of the calice, but do 
not quite meet. In the elongated calices, however, the longest from 
the opposite sides meet in the middle line. The others are too 
irregular to be determined. All the septa are of medium thickness, 
which they maintain as they pass inwards. In an unworn calice 
they all have margins which are regularly tuberculated, about eight 
to ten prominent tubercles being observable on the longer ones. 
The tallest specimen I have seen measures four inches in height, 
and has a diameter of about two inches. Diameter of the calices 
from one and a half to two lines. 
Gemmation and fissiparity occur quite freely and with about equal 
frequency on all parts of the corallum. 
I have examined several specimens from the Lower Lias of the 
Hast Cliff, Lyme Regis, and I possess one which was taken from the 
gravel-pit at Charlton, near Evesham. 
HETERASTRHA REGULARIS, sp. nov. Pl. VII. Fig. 7. 
The corallum of all the specimens I have seen was attached by a 
small oblong space, from which it expanded rapidly, and was sur- 
mounted by an irregular overhanging flattened or rounded top, with 
some elevated lines and gibbosities. The corallites are rather small 
and angular, and, generally speaking, hexagonal, and their union 
with each other is indicated by a fine but very distinct line. The 
calices are deep, almost as deep as wide, and. the walls are regular, 
thin, upright, and straight between the angles. The septa are rather 
regular, straight, and rather thick, and they hold their thickness 
quite into the centre of the calice. There are six systems, and three 
cycles and a rudimentary fourth. The septal edges have large 
rounded denticulations, which are few in number and lobular. The 
primary septa are six, and they unite in the centre of the calice and 
form a false columella, which, however, is not very apparent until 
the tabulz forming the floor of the calice have been broken through. 
