Rev. T. Hincks on the Genus Retepora. 363 
not always been able to detect, even when it is not concealed 
by the apex of the suboral avicularium. The latter is not 
always present ; but it must be accounted a characteristic fea- 
ture of the species. It is immersed, extending from a depres- 
sion situated about halfway down the cell, or less, to the lower 
margin of the mouth, on which its pointed extremity rests. 
It is rounded below and is furnished with a short mandible, 
very broad at the base, and tapering to a fine point. Very 
characteristic also is the flat, smooth, polished and tinted 
surface of the cell, bordered by a distinct raised white line, 
and sparsely punctured round the edge. The punctures or 
foramina are of very considerable size; two are generally 
placed side by side at the bottom of the cell. 
I have examined many fragments of this fine species; but 
the only perfect specimen which I possess is of a compressed 
cup-shape, with the lamina gracefully curved and the margin 
sinuated. The cup is much flattened at one side; and on the 
other side, which is greatly produced, it widens out and then 
terminates in a pointed spout-like projection. The height 1s 
half an inch, andthe width aninch. ‘Lhe formis a singularly 
elegant one, even for a Retepore; but in this genus the habit 
of growth is so variable that it cannot be relied on as a 
specific character. 
3. ? Retepora granulata, Macgillivray. (Pl. XIX. figs. 13-15.) 
Zoarium cup-shaped, thick. Fenestre very small, oval or 
subrotund, much narrower than the very broad interspaces. 
Zooecia rhomboid, flat, lined round, the surface covered with 
granules, which often form a border or edging round the upper 
margin of the mouth; orifice suborbicular, somewhat ex- 
tended transversely ; peristome not raised; frequently one or 
two small oval or subcircular avicularia placed transversely 
immediately below the inferior margin ; many such avicularia 
scattered over the surface of the cells; numerous blunt and 
low mamillz distributed over the zoarium, bearing on the 
upper side an avicularium with broad triangular mandible. 
Ooecta large, prominent, subglobose, surface granular, no 
fissure. Dorsal surface indistinctly vibicate, with scattered 
circular avicularia, sometimes absent. 
Locality. South Australia. 
This is probably the R. granulata of Macgillivray—though, 
in the absence of a sufficiently minute diagnosis of the latter, 
I hardly venture to identify the two with certainty. Amongst 
my specimens there is much difference in the degree in which the 
surface is granulated. In some cases the cells are almost 
smooth; in others the surface is thickly studded with small 
