REPORT ON THE POLYZOA. 
117 
But the avicularian mandibles are very peculiar, and sufficient to establish a distinction 
from those of any other species I have as yet examined. They are all of a very delicate 
membranous texture, with a small occlusor muscle inserted quite at the base, and having 
merely a very slight chitinous border at the lower part and no foramen. The avicularia, 
therefore, would seem to be of the “ retentive ” rather than the prehensile type, whilst in 
Retepora cellulosa, either from Spitzbergen or the Mediterranean, the avicularia are of 
the “ prehensile ” kind, and have the mandible adapted for forcible closure, and furnished 
with the usual long and powerful occlusor muscles, inserted high up, and with the usual 
foramen (woodcut 25, cl). It should be noticed also that in Reteporci cellulosa the rostri- 
form avicularia stand horizontally out from the surface of the zooecium, instead of sloping 
directly downwards as they do in Retepora atlantica. 
§§ 3. Ooecium with a trifoliate stigma 1 in front. 
(10) Retepora victoriensis, n. sp. ? (PI. XXVII. fig. 7). 
(?) Retepora carinata, Macgilliv. 
Character. — Zoarium crateriform or widely infundibuliform. F enestrse oval, distant, 
uniform ; trabeculae wide. Zooecia (young) barrel-shaped or subcylindrical, wide at top ; 
(older) flattened, subrhomboidal, parted by indistinct septal lines ; 
wall smooth, entire, or very minutely and sparsely punctured. 
Peristome thin, usually raised in front or occasionally widely 
canalicular, with a short submedian fissure and small pore ; one 
angle of the fissure often thickened and supporting a minute 
elongated avicularium. A long articulated and jointed spine on 
one, or sometimes on both, sides of the orifice and occasionally in 
the young zooecia one or two slender non-articulated spines on the 
opposite side. Orifice (primary) in quite young zooecia arched, 
with a straight entire lower lip, and sometimes a notch on either 
side. Ooecia large, prominent, strongly umbonate in front, and 
beneath the umbo an obscure trifoliate stigma. Anterior avicularia 
of several kinds ; one of large size on low tubercular circular elevations, with a semi- 
1 This very peculiar mark on the front of the ocecium, probably indicating the way of exit of the mature embryo, 
though noticed by Mr. Macgillivray more than twenty years ago, does not appear to have attracted subsequent atten- 
tion, except in one instance, where Mr. Hincks in redescribing Retepora monilifera (1878) adverts to it “as a granulated 
rim above the upper edge of the aperture, from the centre of which a somewhat clavate band, also granulated or headed, 
extends upwards almost to the top of the ovicell.” Though forming the foundation of Mr. Macgillivray’s name, it will 
he seen that this mark is by no means confined to that species, but may rather he regarded as more especially charac- 
teristic of the Australian Reteporce, amongst which I am not aware that more than one ( Retepora fissa (?) = Retepora cellulosa, 
Macgillivray) has hitherto been known with a vertical fissure. The Challenger Collection, out of nearly thirty 
species, affords a second instance ( Retepora crassa ), certainly distinct from Mr. Macgillivray’s, whilst the same collec- 
tion affords at least thirteen furnished with the trifoliate stigma. 
Fig. 26 . — Retepora 
victoriensis. 
