172 
THE VOYAGE OF H.M.S. CHALLENGER. 
thickened peristome, supporting on each side a small avicularium with a pointed sub- 
triangular mandible. Primary mouth clithridiate with an operculum of corresponding 
form. 
In a paper on some Polyzoa from the Queensland Coast, Mr. W. A. Haswell describes 
a species referred by him to the genus Myriozoum, with the specific name australiense. 
Before this paper came under my notice I had already described and prepared figures of 
the same species in the Challenger Collection and named it Tessctradoma verticillatum, 
which specific name of course must yield to Mr. Haswell’s appellation, and as it appeared 
to me on further examination that the form could not be included under Tessaradoma, 
notwithstanding the presence of a suboral pore, I had like Mr. Haswell subsequently 
referred it to Myriozoum. But I have since come to the conclusion that notwithstanding 
certain points of resemblance it would be forcing the relation much too far to join 
it to the group of which the well known Myriozoum truncatum is the type. I have 
consequently thought that it might form the foundation of a distinct generic group, 
as another member of which I would add with much doubt a second species in the 
present collection, Haswellia auriculata, which, as in the case of Haswellia australiensis, 
I had originally referred to Tessaradoma and afterwards to Myriozoum. 
(1) Haswellia australiensis, Haswell (sp.) (PI. XXIV. fig. 9). 
Myriozoum australiense, Haswell, Proc. Linn. Soc., N. S. Wales, vol. v. pt. 1, p. 33, pis. i iii. 
1880. 
Character . — Zoarium composed of short branches diverging dichotomously at wide 
angles and each containing four to five whorls of cells, each whorl composed of from six to 
eight or ten cells. Zooecia completely immersed so that no outline is visible except the 
much produced tubular peristome, the anterior lip of which (when perfect) is trifid, each 
lateral tooth supporting a small avicularium with a subtriangular pointed mandible ; the 
posterior lip finely crenulate. Primary mouth at bottom of tubular portion clithridiate, 
bidenticulate, and closed with a strong chitinous operculum of corresponding form and 
about 0 r/, 00 7 x ‘005 in size. In front of the tubular portion a rather large rounded 
pore formed at the bottom of a median fissure. Surface uniformly pitted or reticulato- 
punctate. Minute immersed avicularia with an acicular mandible pointing downwards, 
in the sulci between the zooecia. 
Habitat. — Station 186, lat. 10° 30' S., long. 142° 18' E., 8 fathoms, coral mud. 
Station 190, lat. 8° 56' S., long. 136° 5 ' E., 49 fathoms, green mud. 
At first sight the tubular production of the peristome with the pore on its front 
presents a very strong resemblance to Tessaradoma, but the pore is of a totally different 
