14 THE VOYAGE OF H.M.S. CHALLENGER. 



possession of an intermediate or azygos set of zooecia on tlie 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, M^m. Bui. Polypi della Famiglia Tubuliporiani, p. 12 {teste 

 Heller); Heller, Adriat., p. 121 ; Busk, Brit. Mua. Cat., pt. iii. p. 13, pi. xii.; Waters, Haswell. 

 t Tervia folini, Jullien, Bull Soc. 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 O'l to 0"15 mm.; surface uniformly and thickly punctate ; dorsum with 

 longitudinal striae wide apart. Ocecial chamber 1 



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 Jissurata, n. sp. (PL HI. 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"15 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 I'l mm. 

 apart. Surface of branches in front and behind deeply and irregularly sulcate and 

 pitted. 



Habitat— Sta.tion 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 froni; 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. 



Homera, Lamx., Expos., p. 41 (1821); Milne-Edwards (pars), Reuss (pars), Blainville (pars)^ 



Defiance, Michelin, Hagenow, d'Orbigny, Smitt, Hincks, Busk, Sars, &c. 

 Millepora (pars), Linn^, Pallas, Esper, Solander. 

 Retepora (pars), Lamarck, Goldfuss. 

 Syphodictyum (pars), Lonsdale. 



