SPONGES FEOM POKTUGAL. 209 



shapes, or whether this appearance is due more to the 

 direction of the section passing at different angles through 

 the chambers, is difficult to decide. 



The skeleton is composed of seven kinds of spicules : 

 (1) Gastral tetracts, the facial rays measuring 0*132 to 

 0'16 mm. by 0*004 to 0*008 mm., the apical ray 0*056 to 

 0*076 mm. by 0*004 to 0*008 mm. (2) Subgastral triacts, 

 the basal ray 0*28 by 0*012 mm., the oral rays 0*092 to 

 0*1 mm. by 0*012 mm. (3) Subdermal triacts, fewer in 

 number than the subgastral triacts, but of about the 

 same dimentions. (4) Dermal triacts, regular, each ray 

 0*1 to 0*12 mm. by 0*01 mm. (5) Huge oxea, 1*2 to 2*5 

 mm. by 0*06 to 0*09 mm., occurring both in the gastral 

 and dermal cortex and arranged parallel to the long axis 

 of the sponge. (6) Ehabds, situated in the dermal cortex 

 and projecting at right angles, 0*2 by 0*0025 mm., or 

 longer. (7) Oscular rhabds ; 1*2 to 2 mm., by 0*007 mm., 

 forming a dense fringe. 



Heteropegma nodus-gordii, Polejaeff (7). 



Represented in our collection by a single small colony, 

 easily recognised by the huge subdermal tetracts. Pole- 

 jaeff described this species first as from off the Bermudas 

 and Cape York. 



SILICEA. 



Order Monaxonida. 



Halichondria, sp. ? 



A single small encrusting specimen, 2 mm. in thickness, 

 yellowish-grey (in spirit), very soft and pulpy. Oxea 

 0*125 by 0*005 mm. 



Beniera (cinerea, Grant ?) . 



Fistulous, consisting of three conical branches, the 

 largest of them being 22 mm. in height, 12 mm. in its 

 greatest diameter, and the osculum 3 mm. in diameter. 



