444 COLLECTIONS FEOM MELANESIA. 



but fibre more constantly stout ; thickness from "07 to 2 millim. ; 

 meshes narrower, viz. -09 to -7 millim. in smaller diameter, and 

 bearing short blunt processes at intervals, echinated by thick tufts 

 of the smooth subspinulate spicule on its upper surface. Sarcode 

 very dark yellowish brown, granular and opaque. 



Spicules :^(1) Stouter, smooth, subspinulate acuate, straight, 

 with very slight constriction marking off a short head, which is 

 less in diameter than the middle of the shaft ; shaft tapering 

 gradually to sharp point from about centre ; size "23 by "0127 mOlim. : 

 iii tufts on dermal skeleton. (2) Slender, smooth, spinulate, 

 with slight oval head, nearly straight; tapering to sharp point 

 from near centre ; size "35 by '0085 millim. : forming axis of 

 skeleton-fibres. (3) Subspinulate spined acuate, with small glo- 

 bular head, and tapering to a fine point from about centre ; spines 

 numerous, sharp, projecting at right angles to long axis of spicule, 

 prominent on middle of spicule and sometimes on head^ becoming 

 obsolescent in the other parts ; size -09 by -0079 millim. : echinating 

 the skeleton-fibres. (4) Tricurvate acerate of sarcode, smooth, sharp- 

 pointed ; curves gentle ; size about "063 by -0015 millim. (5) Navi- 

 cular equianchorate ; shaft slender, slightly curved ; length about 

 •0127 millim. 



Hab. Thursday Island, Torres Straits, 3—4 fms., bottom sand ; 

 also same locality, probably from beach. 



Two specimens, agreeing closely in their characters, represent the 

 species ; heights 70 and 85 millim. (2^ and 3|- inches) respectively ; 

 expanse of branches 30 and 20 millim. respectively. It agrees 

 closely in character of spiculation with 0. ulmus, Vosmaer (Notes 

 Eoy. Mus. Netherl. ii. p. 151), of which the locality is not stated ; 

 but the stem is single and not ramified as stated by Vosmaer, who 

 does not mention the most striking external characteristic of this 

 species, viz. its strong aculeation by long pointed processes. I know 

 of no other species which approaches it at a,ll closely. 



75. Clathria tuberosa. (Plate XLII. fig. d.) 

 Microciona tuberosa, Bowerbank, P. Z. S. 1875, p. 281. 



The specimens are finer than those in the Bowerbankian collec- 

 tion ; the largest measures 70 millim. (2f inches) in greatest dia- 

 meter, and 50 millim. (2 inches) in greatest height ; the individual 

 lobes may measure as much as 14 millim. in greatest diameter. 

 The " skeleton columns " (Bowerbanh) are even more strongly 

 arenated than in the type specimen, and resemble those of a Dysidea, 

 the projecting ends of the spined and fine smooth acuate being the 

 only point of difference which appears at first sight. The propor- 

 tions of the spicules differ slightly from those of the Malacca speci- 

 mens as given by me (P. Z. 8. 1881, p. 121)*, viz. : — 



* The length of the equianchorate should hare been stated there as 016 

 millim., and the base of the slender smooth acuate described as slightly inflated. 



