a General History of the Marine Polyzoa. 9 
Loe. Off Curtis Island, on shell, forming a large spreading 
atch. 
This handsome species belongs to the same group as C. 
Jigularis. 
Cribrilina monoceros ?, MacGillivray. 
(Pl. III. fig. 6.) 
Zoecia subcylindrical or ovate, flattish, separated by a 
smooth raised line, highly calcified and confluent in older 
states; the whole of the front surface pierced by numerous 
holes of various shapes and sizes, some of them large; orifice 
well arched above, lower margin straight, with a strong central 
mucro, on the front of which is a small pointed avicularium, 
the mandible directed upwards ; immediately above the orifice 
two or three small pointed avicularia; four oral spines, two 
on the upper margin, tall, slender, forked at the extremity, 
and two (placed one on each side) just within the peristome, 
immediately above the lower margin, articulated, tall and very 
stout, forked ; frequently great numbers of avicularia of vari- 
ous forms distributed over the zoarium. Occium rounded, 
subimmersed, smooth, often with a thickened rib round the 
opening, and bearing usually several small avicularia, closed 
by a large, dark-coloured operculum. 
Loc. Bass’s Straits, very common on shells, Retepore, &e. 
I refer this form doubtfully to the Lepralia monoceros of 
MacGillivray. Ifthe two are indeed identical, his brief de- 
scription must have been founded on imperfect specimens ; for 
it omits some important characters, such as the avicularium 
on the mucro and the forked spines. 
The species varies much with age, and in its older states 
presents a flat uniform surface (the boundaries of the cells 
being obliterated) completely covered with large perforations. 
When young the surtace is bright and somewhat shining. 
There is sometimes only one of the large articulated spines *. 
In certain states there is a remarkable profusion of avicularia 
of various forms: some, very large, elongate, raised and 
laced on a distinct area, occur chiefly on the margin of the 
colony (Pl. III. fig. 6a); others of a smaller sizé and sessile 
are scattered abundantly over the cells, whilst occasionally a 
very different kind is present in great numbers, which is erect, 
and rises considerably above the surface, rounded on one side 
and having on the other a triangular mandible, directed 
straight upwards. I have also met with a spatulate form. 
* MacGillivray’s description, ‘a large thick vibraculum or spine below 
the mouth on one side” does not apply to this appendage, which is placed 
within the peristome. 
