REPORT ON THE MONAXONIDA. 201 



smaller, which are about 0'07 mm. in diameter and are the true pores ; these pores lead 

 into well-developed subdermal cavities between the ends of the radiating skeleton fascicles. 



Skeleton. — Radiately arranged, composed entirely of tylostylote spicules. There 

 is a dennal crust of small tylostylote spicules arranged in closely placed, but not 

 very tightly packed, divergent brushes, the points of the component spicules projecting 

 freely beyond the dermal membrane and giving rise to the hispidity already mentioned. 

 The main skeleton is composed of radiating fascicles of large tylostylote spicules, running 

 vertically to the surface and there ending in the brushes of small spicules which form the 

 dermal crust ; between these main fascicles are scattered other tylostylote spicules. 



Spicules. — Megasclera; of one form only, viz., smooth tylostyli (PL XLV. figs. 

 3, 3a, 36), straight or slightly crooked, slightly fusiform, with well-developed, hemi- 

 spherical or nearly globular heads, and fairly sharply but rather suddenly pointed at 

 the apex. These spicules are very variable in size ; small ones are found in the dermal 

 <;rust and large ones in the deeper parts of the skeleton ; the range in length is about 

 from 0"2 to 1'2 mm. and in diameter about from 0"0078 to 0'03 mm. The spicules of 

 the dermal crust commonly measure about 0'28 by 0*0126 mm.; those of the deeper 

 skeleton about TO by 0'025 mm.; but there is great variation. 



This is a remarkably fine species and shows the oscula and pores (which are often 

 extremely difiicult to make out in the genus Suberites) very distinctly.^ Its dis- 

 tinguishing characters are the general external ajapearance, the hard texture and the 

 incipient stalk ; in the latter point it approaches Suberites axiatus (below). 



Locality. — Port Jackson ; depth, 30 to 35 fathoms. One fine specimen. 



Suberites antarcticus. Carter (PI. XLV. fig. 7, 7a, 7b, 7c, 7d). 



1876. Suberites antarcticus, Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xviii. p. 391. 



Sponge erect, much branched, bushy ; branches long, cylindrical, may anastomose on 

 coming into contact with one another. Total height of Challenger specimen about 

 150 mm. ; greatest breadth about 50 mm., diameter of branches 6 to 8 mm. 

 Colour in spirit black (colouring (?) the spirit deep amber). ^ Texture firm, but a little 

 spongy. Surface fairly even, but minutely reticulate and also very minutely hispid ; 

 harsh to the touch. Dermal membrane delicate, transparent, difficult to make out. 

 Oscula numerous, small, distinct, scattered over the branches, sometimes placed serially 

 one above the other, each on the top of a small, low papilla. The excretory canals can 

 be very distinctly seen through the skin, converging towards the oscula in a stellate 

 manner. Pores apparently arranged as in Suberites perfectus, nobis, but not clearly 

 made out. 



' Further details with regard to the anatomy and histology will be found in the Introduction. 

 = It is possible that this colour is due to other sponges packed in the same vessel, but Mr. Carter's type specimen in 

 the Britis-h Museum seems to indicate otherwise. 



(zooL. CHALL. EXP. — PART OX. — 1887.) Nnn 26 



