434 COLLECTIONS PROM MELANESIA. 



primary skeleton-fibres ; the canals I have mentioned range in dia- 

 meter from about -07 to -14 millim. This opening of a considerable 

 proportion of the ciliated chambers directly into moderately wide 

 canals agrees with what Vosmaer finds to be the arrangement in 

 many forms of the other Monactinellid families Eenierids and Sub- 

 eritidse, as well as in a few other forms, viz. his third type (' Antee- 

 teningen over fjeucandra aspera, H.,' Leyden, 1880, and Tijdschrift 

 Nederl. Dierk. Vereen. v. p. 144 et seq.). 



67. lotrochota purpurea. 

 (Plate XXXIX. fig. L; Plate XLII. figs, e-e"".) 



Halichondria purpurea, Bowerbank, P. Z. S. 1875, p. 293. 



Dr. Bowerbank's specimen (from the Straits of Malacca) is evi- 

 dently quite young ; the present fine series of specimens, both dry 

 and in spirit (numbering upwards of twenty), gives a better idea of 

 the characters of the species. 



The external form is usually that of a cylindrical column, narrow, 

 diminishing gradually in thickness towards apex, viz. from about 15 

 millim. at base to 4 millim. at apex in. adult specimens, dividing 

 towards the apex into two or three subequal branches ; it is some- 

 times flattened irregularly near the base ; it occasionally forms a 

 broad palmate frond or irregular erect expansion, or an irregularly 

 honeycombed horizontal mass which may attain a diameter of 65 

 millim. (2^ inches). The surface is broken up into a forest of 

 pointed or ridge-like monticular elevations, 1-3 mOlim. apart, 1-3 

 millim. high. In the typical specimen (dry) the surface aculeations 

 are only -5 to 1 millim. apart and the same in height. Texture in 

 spirit rather firm, but soft on surface, tough and flexible ; in dry 

 state harsh on surface, rather brittle : colour in spirit very deep, 

 purple, in dry state dark green or pale purple. Skeleton rectangular, 

 consisting of stout compact primary spiculo-fibres devoid of visible 

 horny material, 10 to 20 spicules broad, and of similar secondary 

 fibres 1 to 3 spicules broad. Skeleton-spicules sipooth, acuate, 

 rather squarely rounded at base, tapering to a sharp point from about 

 five diameters from end ; size chiefly -26 by "0063 mUlim., a few 

 in the interior of the primary fibres -18 by -005 to -0095 miUim. (in 

 the type the prevailing size is -16 by -0127 millim. and the spicule 

 frequently increases in diameter from the base towards the centre). 

 Flesh-spicule birotulate (not equianehorate, as stated by Bowerbank), 

 shaft very slender ; rotulae small, umbrella-shaped, with four equal 

 curved teeth ; length of spicule -016 to "019 millim. Sarcode in 

 spirit dark purple, granular ; in dry state either dark purple or dark 

 greenish. Large specimens attain a height of about 150 millim. 

 (6 inches). 



Mab. Torres Straits, various localities down to 10 fms. ; Albany 

 Island, 3-4 fms. ; Port MoUe, coral-reef. 



Distribution. Straits of Malacca (^Bowerhank). 



The specimens referred to as being greenish in colour are all drj-. 



