184 
THE VOYAGE OP H.M.S. CHALLENGER. 
over, primary orifice arched above and sinuate below ; afterwards crescentic and narrow 
owing to the rising in front of it of a thick transverse bridge beneath which is formed the 
suboral pore, often divided into two ; and on each pier of the bridge a minute avicularium. 
Avicularian cells all marginal, with a short strong curved mandible pointing upwards. 
Habitat. — Samboangan, 10 fathoms. 
The chitinous appendages shown in the woodcut consist of a, a, probably immature 
zooecial opercula which are rare ; b,b, ooecial opercula ; c,c,c,- zooecial opercula, which are 
thick and solid and often cracked down the middle ; d, the mandible of a marginal 
avicularium ; e,e, mandibles of frontal avicularia. 
(2) Adeonella platalea, Busk (PI. XXI. figs. 4, 4a, excluding the branched figure). 
Esehara platalea, Bk., Brit. Mus. Cat., pt i. p. 90, pi. cv. figs. 1, 2, 3, and pi. eviii. fig. 4 ; 
Macgilliv., loc. cit., Dec. vol. v. p. 41, pi. xlviii. fig. 4. 
? Eschara hexagonalis, Haswell, Proc. Linn. Soc. New South Wales, 1881, vol. v. p. 41, pi. iii. 
figs. 1, 2. 
Character . — Zoarium branched or irregularly lobate. Cells trimorphous. Zocecia 
very uniform, hexagonal ; convex or tumid in front 
with a smooth, uneven, entire surface, obscurely pitted 
round the border ; in the older cells hollowed slightly 
in front. A large circular pore placed in the upper 
part of the front, on the sides one or more small 
avicularia (often absent). Orifice orbicular, with a 
thick rounded entire peristome. Ooecial cells larger, 
barrel-shaped, the wall closely punctate. Orifice 
(primary) broadly clithridiate or sinuate, afterwards 
semicircular or subcrescentic ; a large suboral pore 
formed by the inarching of two tubercular processes, 
one on each side of the orifice and forming a bridge, 
beneath which is the pore, often divided into two ; 
and on either side of the bridge a minute avicularium. 
Avicularian cells marginal or sometimes intercalated, 
the latter having a strap or spoon-shaped mandible. 
Habitat . — Station 201, lat. 7° 3' N., long. 121° 
48' E., 82 to 102 fathoms, stones and gravel. 
[Bass Strait ; off Cape Capricorn, Voy. of Rattles. ; 
Queenscliff, Victoria, Macgillivray.] 
Fig. 50 . — Adeonella platalea. a, a, a, Zooecial 
opercula ; b, an ooecial operculum ; c,c,c, 
frontal avicularia ; d, one of the intercalated, 
avicularia ; e, one of the marginal avicularia ; 
/, primary mouth of a zooecial cell ; y, a 
secondary mouth. 
The specimens of this species in the Challenger 
Collection are only a few small fragments, but in fair condition and sufficient to render 
