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



The column is in some places about 30 mm. high, but in others not moj:e than 15 mm. ; 

 where it joins the cajiitulum, it becomes divided into a number of buttresses, corre- 

 sponding in great measure to the lobular divisions of the head. It is of a firm rigid 

 nature. 



The capitulum is of a very irregular outline, consisting of at least five lobes, each of 

 which forms a tongue-like mass, folding down over the column, and being applied to it ; 

 these lobes, by mutual growth against one another, become more or less elongated, and 

 have their edges very deeply inverted. The broader diameter of the capitulum is about 

 50 mm., with an average narrow diameter of 35 mm., and a depth of 5 mm. The 

 irregular basal diameter of the column is 100 mm. 



The surface of the capitulum when dry is firm, rigid, and somewhat smooth. 



The autozooids are numerous; they occur all over the surface of the capitulum, and are 

 arranged with a certain regularity in spiral rows. In a dried morsel the polyp orifices 

 are 0"5 mm. in diameter, with an average distance between each of TS mm., and the 

 same between the rows. The polyps are as usual completely retractile within cavities in 

 the mass. 



The siphonozooids are also numerous, and appear to be arranged in circles around the 

 autozooids; about four can usually be counted from one autozooid to another; they seem 

 more conspicuous than usual in this genus. 



The mesoderm seems largely strengthened by spicules. The colour is a dark brown. 



The spicules of the sterile stem measure — the tuberculated spindles 0"4-0"16 ; 

 0-36-0-2; 0-34-0-2 ; 0-3-0-1 ; 0-28-0-1 mm. In the capitulum the straight or curved 

 spindles measure 0'32-0'6 ; 0'3-0'06 mm. ; the clubs with bifid or spiny heads 0'2- 0'08 ; 

 0-14-0-06 mm. ; the four-rayed forms 0-14-0-14 ; 0-12-0-08 mm. 



The above details are given, because we have not had the opportunity of a comparison 

 with the type species of either Klunzinger or Marenzeller ; the varieties of this species 

 are also very numerous. 



Habitat. — Eeefs, Fiji. 



Genus Lobophytum, Marenzeller. 

 Lohophijtum, Marenzeller, Zool. Jahrb., BJ. i. p. 352, 1886. 



Colony not mushroom-shaped. Polyps dimorphic both autozooids and dot-like 

 siphonozooids, occurring only on the lobes. 



The colony gives rise to lobe-like or finger-shaped processes from its upper surface, 

 which scarcely overhang the sterile basal portion. The upper surface of the polyp- 



