462 Rev. T. Hincks on the 
falls into the groove traversing the beak; usually at the 
bottom of the area a prominent sessile aviculartum with pointed 
mandible. Vibracular cell wedge-shaped, the terminal groove 
stretching transversely across the back of the cell; seta rather 
long and very slender. Oaciwm subglobular, smooth and 
shining. 
Height of the tuft $ an inch. 
Loc. Off Cumshewa Harbour, growing on shell. 
The remarkable point in the present species is the curious 
modification of the lateral avicularium. In form and struc- 
ture the avicularian appendages are, as a rule, more constant 
in this and the kindred genera than in most other sections of 
the Polyzoa. I know of no deviation from the ordinary type 
except in the present case and in a species (which I hope 
shortly to describe) which is furnished with an elongate, sub- 
spatulate avicularrum, very unlike the normal form of the 
appendage in this tribe. 
In 8S. varians both the ordinary and the modified form of 
the avicularium occur on the same specimens; the two are 
intermingled, but the latter is much the more abundant. I 
venture to think that we have here additional evidence of a 
very striking kind, of that instability of the avicularian struc- . 
ture, upon which I have often insisted. 
Apart from its avicularium, S. varians presents no very 
striking features; and, of course, the variability in this organ 
would not in itself constitute a specific distinction. In other 
respects, however, it is, I believe, sufficiently distinct from the 
various described forms. 
Scrupocellaria brevisetis, n. sp. 
Zoecia biserial, alternate, elongate, tapering downward, 
surface smooth and glossy; area oval, about half the length of 
the cell or less, set somewhat obliquely, surrounded by a rather 
broad smooth border; three spines on the outer side above, 
and one or two on the inner; operculum small, placed about 
the middle of the inner side, when mature entire or with a 
slightly irregular margin, narrow towards the base, expanding 
above it, surface smooth. Lateral avicularium sometimes 
gigantic and much swollen below, sometimes very small, with 
a triangular mandible somewhat bent at the apex; the beak 
strongly hooked. Vibracular cell placed just above the lateral 
avicularium, rounded and somewhat contracted below, ex- 
panding very slightly upward, truncate above, a constriction 
about the middle, immediately below which is the orifice from 
which the radical fibre springs, the terminal groove straight 
or slightly oblique, stretching across the back of the cell; 
