14 
THE VOYAGE OE H.M.S. CHALLENGER. 
possession of an intermediate or azygos set of zooecia on the front, and, it may be added, 
by the circumstance that the outermost zooecium in the lateral series is the longest. 
(7) Idmonea irregularis, Meneghini. 
Idmonea irregularis, Meneghini, Mem. sui Polypi della Famiglia Tubuliporiani, p. 12 ( teste 
Heller); Heller, Adriat., p. 121; Busk, Brit. Mus. Cat., pt. iii. p. 13, pi. xii.; Waters, Has well. 
1 Tervia folini , Jullien, Bull. Soe. Zool. de France, vol. vii. p. 501, pi. xiii. figs. 8-9, 1882. 
Character. — Zoarium composed of irregularly dichotomous, slender, rounded branches, 
0‘5 to 0'6 mm. wide. Zooecia four to six in each lateral series, and the intermediate space 
in front occupied by numerous others irregularly scattered; series 0'6 to 0'8 mm. apart. 
Diameter of zooecia 0‘1 to 0 H 5 mm.; surface uniformly and thickly punctate ; dorsum with 
longitudinal striae wide apart. Ooecial chamber % 
Habitat. — Station 75, lat. 38° 38' N., long. 28° 28' 30" W., 450 fathoms, volcanic 
mud. 
[Adriatic, Meneghini, Heller; Mediterranean, H.M.S. “Porcupine"; Bay of Biscay, 
Jullien ; Bay of Naples, Waters ; Queensland, Haswell.] 
(8) Idmonea fissurata , n. sp. (PI. III. fig. 5). 
Character. — Zoarium procumbent, composed of branches radiating irregularly from a 
central peduncle, dividing about twice dichotomously and appearing strongly serrated 
on the borders ; branches 0’7 to 1 mm. wide. Zooecia 0'1 5 to 0'2 mm. in diameter, with 
an elliptical aperture, closely adnate, the outermost the longest ; a few isolated median 
zooecia whose apertures are Usually level with the surface. Lateral series 0‘9 to 1H mm. 
apart. Surface of branches in front and behind deeply and irregularly sulcate and 
pitted. 
Habitat. — Station 320, lat. 37° 17' S., long. 53° 52' W., 600 fathoms, green sand. 
This species is at once recognisable by the peculiar fissured aspect of the surface, both 
in front and behind, and the numerous irregular pits with which it is studded. Its habit 
in some specimens is something like that of Idmonea radians, but much stronger. Like 
the others of the group to which it belongs, the branches appear serrated on each side. 
2. Horner a, Lamouroux. 
Hornera, Lamx., Expos., p. 41 (1821) ; Milne-Edwards (pars), Reuss (pars), Blainville (pars), 
Defrance, Michelin, Hagenow, d’Orbigny, Smitt, Hincks, Busk, Sars, &c. 
Millepora (pars), Linne, Pallas, Esper, Solander. 
Retepora (pars), Lamarck, Goldfuss. 
Syphodidyum (pars), Lonsdale. • 
