12 C. F. JBNKIN. 



upwards, 80 /a to 150/* long X 8 to 10 m thick. Oral angle 110° to 125°. 

 Occasionally a t shaped variety is found. 



The Quadriradiates are of one sort : 



(c) Large alate quadriradiates from the gastral layer. Basal ray straight, 



tapering uniformly to a very sharp point, 420m to 680m long X 10/u, 

 thick. Paired rays equal, bent slightly downwards near the centre, then 

 straight, 330 m to 380 m long X lOju, to 11m thick. Oral angle 140° to 

 150°. The T shaped variety is fairly common. Apical ray slightly bent 

 orally, sharply pointed, 50 m long x 8 ju, to 12 m thick. Occasionally the 

 apical ray appears to be wanting. 



Oscular spicules. 



(d) The oscular fringe consists of hair spicules over 400 m long. 



The triradiates are the same as (b) ; the quadriradiates are similar to (c), only 

 much smaller. The projecting oxea are the same as the smaller sizes of (a). 



Tenthrenodes antarcticxjs. 



(Plate XXIX., Figs. 28-32.) 



There are three specimens of this new species in the collection ; they are easily 

 distinguished by the naked eye from T. scotti, owing to their having bare basal tubes 

 and bare oscular collars, so that the sponge presents the appearance of an oval ball 

 pierced by a tube. The dimensions of the three specimens are : — 



11 mm. long x 3 mm. diameter. 

 4 mm. „ X 1 "2 mm. ,, 

 10 mm. ,, X 1 '6 mm. ,, 



In colour they are white as preserved in spirits. 



The flagellated chambers are branched near their proximal ends, and each opens 

 directly into the gastral cavity through a contractile apopyle. They have articulated 

 skeletons which terminate at the distal end in freely projecting cones of triradiates, 

 amongst which are a few small oxea (see Fig. 28). 



The gastral skeleton (see Fig. 29), consisting of large tri- and quadriradiates, 

 extends the whole length of the tube. 



The oscular edge has a very regular skeleton of small quadriradiates closely 

 packed together, with a fringe of hair oxea (see Fig. 30). Unfortunately the 

 specimens are not in a sufficiently good state of preservation to allow the exact 

 structure of the basal tube to be made out. There are indications of a lining of 

 flagellated cells in the basal tube, continuous with the lining of the lowest radial 

 flagellated chambers. These chambers appear to arise as bulgings of the gastral layer. 



