3 
This is marked transversely by irregular growth ridges and a 
chevron-like ornament. 
The dimensions of the type are:—Length of corallum from 
base of pedicel to summit of wall, 22 mm. ; five of its roots are 
broken, but the remaining one, which is apparently intact, is 
10 mm. long, and extends 5 mm. beyond the pedicel. Its calice 
is 19 mm. long and 12 mm. broad. Though there is considerable 
variation in the size of individuals, they maintain generally the 
same relative proportions; young examples are, however, com- 
paratively short. 
Specimens of this coral were dredged by Dr. Verco at most of 
the stations from a depth of 15 to 22 fathoms. My collection 
also contains two examples from Port Phillip Bay. 
Genus HorcorRocHus, Dennant. 
Holcotrochus scriptus, Dennant. R.S.S. AR vol; xvi) pp: dg 2. 
PL. i., fig. 1, 
This species was described as a rare fossil from Muddy Creek, 
and the single example dredged in Backstairs Passage shows no 
variation from the type. 
Holcotrochus crenulatus, spec. nov. Pl. ii., figs. 4a, 5, c. 
The sorallum is very small, much compressed, and has a glis- 
tening, minutely granular surface. A deep sulcus around the 
base and edges divides it superficially into two plates, which con- 
stitute the anterior and posterior sides of the coral, and the two 
are then joined together by thin, depressed continuations of the 
extreme lateral coste. These plates have curved and beautifully 
crenulated edges, and are roundly pointed inferiorly. As in 
H. scriptus, there are ten broad costæ, which rise considerably 
above the margin. The interspaces are occupied by ten smaller 
costæ, which just show as finely pointed projections at the margin 
of the calice. These secondary cost: answer to the slender rods 
between the broad coste of the type species of the genus. On 
the flat sides both sets of costæ are marked for about a third 
from the margin, very fine grooves separating them. The coste 
of the edges, like the other primaries, are broad from their 
summits to the calicular margin, but below this they suddenly 
diminish to the thin sunken lines which connect the two halves 
of the corallum. 
The septa are continuations of the primary cost, and thus ten 
in number. They are plain, broad, and free. The calice is ellip- 
tical, and the central fossa is large and deep. There is no 
columella, 
The corallum is 3:5 mm. high ; its calice is 2:5 mm. long and 
1:5 mm. broad. 
