Mr. A. W. Waters on Australian Bryozoa. 15 
Mucronella prestans, H., the whole front of the peristome is 
raised ; in M. porosa, H., there seems to be no true mucro ; 
and in JM. contorta, B., and M. bisinwata, as previously 
pointed out, we ought not to speak of a mucro. 
In Smitiva the oral avicularium may, just as in Porella, be 
enclosed in the secondary aperture, as seen in some forms of 
S. Landsborovit; and, as at present defined, I find myself 
unable to decide what is Pore/la, though perhaps we shall 
find other characters uniting together a part of what is now 
ealled Porelia. 
The mandibles of the oral avicularia of a number of this 
group show a similarity in having a diagonal strengthening 
chitinous bar from each side of the lucida. We may call 
this the Smittta Landsborovit type, represented also by 
Porella cervicornis, Ell. & Sol., P. marsupium, P. levis, P. 
rostrata, Umbonula verrucosa, Smittia rigida, Lorenz; but 
before we can know the value of this character further com- 
parisons of similarly placed avicularia are required. The 
variation in position, size, and direction of the oral avicularia 
of some Schizoporelle, as for instance S. auriculata, must 
put us on our guard against hasty conclusions. 
The Eschara cervicornis of Pallas and M.-Edwards has the 
oral avicularia within the orifice, and I have therefore called 
it Porella; but Mr. Hincks would call it Smdttva, and from 
this I think we may see the artificialness of the genus Porella, 
as at present understood, 
As to the peristomial characters, there is great variety in 
the genus Smttia, and again in Schizoporella there is in many 
species a raised peristome, as, for instance, in Schizoporella 
discoidea, B.; and in several Cellepore, as represented by C. 
granum, the peristome is tubular above the oral aperture. 
Though no doubt often useful specifically, peristomial cha- 
racters do not seem applicable for generic divisions. 
I give a figure of the Smdtt¢a which Dr. Jullien would call 
Exochella longirostris from Cape Horn, as it shows the lyrula 
and cardelle meeting and enclosing a space, and probably 
this is similar to the structure of Smitita tricuspis, H., but 
in the latter the prolongation of the peristome forms a tube 
on each side. 
Dr. Jullien has recently also suggested that IMucronella 
should be dropped ; but I am unable to follow him in the way 
in which he would divide up the group. 
Smittia unispinosa, sp. nov. (Pl. IIT. figs. 1-3.) 
Zoarium incrusting. Zocecia large, quadrate, distinct, with 
