406 COLLECTIONS FKOM MELANESIA. 



nately from one side of the main stem at very acute angles, soon 

 becoming almost parallel Avith the stem itself ; their length varies 

 from 60 to 12<» millim. (2^ to 4| inches). The vents are numerous, 

 •5 to 1 millim. in diameter, circular, with sharp, prominent margins, 

 about -5 to 1 millim. above the general surface ; ranged in a single 

 row down each margin of the stem and branches, and also scattered 

 (more sparsely) on their anterior and posterior faces ; they are 2 to 

 5 millim. apart on the margins. General surface of sponge level, 

 only rendered a little uneven by the slight elevations which carry 

 the vents, composed of a close meshwork ; meshes - 25 wide, -25 to 

 •5 millim. apart. Texture firm, incompressible in stem, elastic, 

 somewhat compressible towards ends of branches, brittle ; the sur- 

 face and internal fibre soft, like leather. Colour in dry state — surface 

 pale grey ; interior brownish yellow in present specimens, owing to a 

 parasitic microphyte of some kind. Sarcode apparently transparent, 

 almost colourless. 



Main skeleton — meshes strictly rectangular, very close ; primary 

 fibres about *11 millim., secondaries about "14 millim. apart near 

 surface ; horny material uniting fibres only visible distinctly at some 

 depth in the sponge ; primary fibres 3 or 4 spicules broad, secon- 

 daries 2 or 3 spicules broad. Dermal skeleton composed of meshes 

 of various sizes and a varying number of angles, formed by the pro- 

 jecting ends of the primary main-skeleton fibres and the uppermost 

 secondary fibres. Horny matter almost colourless. Spicules — (1) 

 skeleton acerate, smooth, slightly curved, tapering to sharp points 

 from near middle ; size -16 by '0063 millim. 



Hah. Friday Island, Torres Straits. 



Distribution. " Probably Indian Ocean " (Lamarck). 



Parasite. The horny matter of the fibres is covered with immense 

 numbers of a small, strongly refractive globular body about *0015 

 millim. in diameter, similar to that which gives a rust-brown colour 

 to the fibres of many Euspongice, recently stated by Prof. F. E. 

 Schulze (•' Der Badeschwamm," Westermann's Illustr. Deutsch. 

 Monatshefte, 1882, pp. 188-210) to be probably of parasitic nature. 

 Certainly, judging by the friable character of these and other simi- 

 larly affected specimens, these bodies would appear to have exercised 

 some distinctly deteriorating influence. 



renierid.e. 



Renierida, Carter, Ann. Sf May. X. II. (4) xvi. p. 133. 



Under this heading I include only those Monactinellida which have 

 merely acerate spicules not enclosed in a distinct horny fibre. The 

 genus Reniera very commonly has strong indications of a horny 

 material uniting the ends of the spicules, and thus approaches 

 Chalina and Pachychalina, where, however, the horny element is 

 distinct enough to bear the name of a fibre ; but there is no sharp line 

 between the Renieridaa and Chalinidae. In several cases, where the 

 sp"cimens have been imperfect, 1 have preferred to give no specific 



