78 records of the australian mttseum. 



Family DESMACIDONID^. 

 PsEUDOiiALiciiONDRiA, Carter. 



PSEUDOHALICHONDRIA FIBROSA, sp. nov. 



(Plate X., fig. 8). 



Sponge subtriangular in outline, consisting of a stout short 

 stem, with numerous compressed branches, more or less disposed 

 in a single plane; their apices attain to nearly tlie same level. All 

 the branches have one or more continuous longitudinal grooves, 

 which in the living sponge probably terminated in oscula ; the 

 grooves are from 2 to 4 mm. in diameter. Surface villous and 

 conulose; the dermal membrane exhibits numerous round pores 

 about 1 mm. in diameter. Texture hard, rather inelastic, but 

 tough, fibrous, and harsh to the touch. Colour in the dried and 

 somewhat water-worn condition, yellowish-gray. 



Skeleton consisting of a rather loose rectangular network of 

 strongly developed fibres. Primary lines rather sinuous, about 

 0'2 mm. in diameter, generally 06 mm. or less apart, cored with 

 abundant cylindrical styli, held together by a minimum quantity 

 of spongin. Secondary connecting fibres usually at right angles 

 to the primaries, and densely multispicular ; they measure from 

 005 to 0-1 mm. in diameter; even in the most slender fibres it 

 is difficult to estimate the number of spicules occuriing in a row. 

 The dermal membrane contains abundant spinose C-shaped micro- 

 scleres, superposed by a dense layer of smooth stylote spicules. 



Megascleres — Straight, smooth, cylindrical styli, with a well 

 rounded base and acute or subacute apex. Size — 0-24: to 027 by 

 0-005 to 007 mm. These occur abundantly in the dermis 

 ground substance and in the fibres. 



Microscleres — Spined isochelje, sparingly scattered through the 

 ground substance, and densely packed in the dermis. Size — 0"018 

 mm. in length. The chelae — apart from their larger size — do not 

 differ from those of Pseudohalichondria clavilobata, as figured by 

 Carter. ^"^ 



This species differs from the type of the genus in the total 

 absence of foreign matter, and in the remarkable development of 

 the fibres. Height 145, breadth 190, thickness from 5 to 15 mm. 



A single specimen was obtained at Lake Illawarra. 



Desmacidon, Bowerbank. 



Desmacidon dendyi, sp. nov. 



(Plate X., fig. 9). 



Sponge massive, light, open, and cancellous throughout. The 

 walls of the reticulated surface have their edges directed outwards, 

 they are slightly conulose and vary between 1 and 2 mm. in 



16 Carter— Ann. Mag. Nat. Hist., (5),xviii., 1886, pi. x., figs. 8a.- cJ. 



