64 
THE VOYAGE OF H.M.S. CHALLENGER. 
number) the border can in none be said to be crenate, nor is it specially entitled to be 
called “ thick,” seeing that it is by no means thicker than in many other allied forms. 
In the figures here given, however, it should be remarked that the border is not shown 
quite as thick as it sometimes is. In Prof. Smitt’s figures it is also shown as very thin. 
§ /3. spinosce. 
(3) Membranipora spinosa, d’Orbigny. 
Membranipora spinosa, d’Orbigny, Voy. en Amer. M4rid., pi. viii. fig. 1. 
„ ciliata, Macgilliv., Nat. Hist. Viet. Dec. iii. p. 30, pi. xxv. fig. 3. 
Character. — Zoarium encrusting ; zocecial areas distant, very regularly oval ; eight in- 
cumbent marginal spines. 
Habitat. — Station 163a, off Twofold Bay, 150 fathoms, green mud. 
[South Patagonia, d’Orbigny ; Australia, Macgillivray.] 
(4) Membranipora galeata, Busk. 
Membranipora galeata, Bk., Brit. Mus. Cat., vol. i. p. 62, pi. lxv. fig. 5. 
Character. — Orifice oval ; margin thin, membranaceons. Two straight, articulated, 
tapering, hollow spines, open at the point on each side above. Ooecium cucullate, 
grooved above the border in front, and crowned with an avicularium with an elongate, 
spear-shaped mandible pointing directly forwards. A long pedunculate, trumpet-shaped, 
avicularium rises from the front below the aperture. 
Habitat. — Station 149d, Royal Sound, Kerguelen Island, 28 fathoms, volcanic mud. 
The peculiar elongated avicularium on the summit of the ooecium is sometimes re- 
placed by one of the trumpet form ; in either case this avicularium properly belongs to 
the superior zocecium. 
Var. a. furcata. 
The lower pair of spines furcate and the anterior avicularium often wanting, 
sometimes sessile and of large size, with a small horn on either side. 
Habitat. — Off Marion Island, 50 to 75 fathoms. Station 150, lat. 52° 4' S.,long. 71° 
22' E., 150 fathoms, coarse gravel. (On Onchopora sinclairii, Salicornaria, sp.) 
Var. b. multifidd. 
Lower pair of marginal spines multifid. 
Habitat. — Simon’s Bay, Cape of Good Hope. Station 75, lat. 38° 38' N., long. 28° 
28' W., 450 fathoms, volcanic mud. (On the test of an Ascidian.) 
