8 C. F. JENKIN. 



botnjoidts. lu }uung specimens tlie trinuUutes arc geuerally .smaller and 

 more slender than in the larger colonics. 



QuadriradiatL's. 



(d) These spicules are generall}' much scarcer than the simple triradiates, l)ut 

 can always be found. Their facial rays are similar to the triradiates, with 

 perhaps slightly less tendency to elongation of the unpaired rays. The 

 gastral ray is short or of moderate length, laterally compressed, and set 

 well back on the unpaired facial ray ; its proximal end runs straight 

 upwards for about two-thirds of its length, then the shaft curves forwards, 

 the distal extremity, however, being again nearly straight. 



SpiciUathin of the Oscidar Rim. 



The skeletal spicules of the oscular rim appear to be quadriradiates alone. 

 They are of relatively small size and slender dimensions ; the lateral angles 

 are very nearly or even quite right angles, so that the spicule is more or 

 less T-shaped ; the unpaired rays are always distinctly longer than the paired, 

 the latter being strongly curved, and the gastral rays are relatively long. 



The monaxons of the oscular rim are, with rare exceptions, of the smallest size. 

 Both ordinary and refringent monaxons are found ; the former differ from 

 those in other parts in the slenderness of the shaft, the proximal end of 

 which is scarcely or not at all swollen. The refringent monaxons in this 

 region are also very slender and sharp. 



Leucosolenia minchini. 



(Plate XXVIII., Figs. 14-15.) 



There are about eleven specimens of this new species in the collection, most of 

 them being oscular tul)es only, with very little root tube. Their appearance and habit 

 of growth are well shown in Fig. 14, drawn by Professor Minchin. The oscular 

 tubes, which are 3 mm. to 4 mm. long, are usually largest towards the middle of their 

 length. Diameter, flattened, about 5 mm. The bulk of the skeleton spicules are 

 triradiates, regularly arranged and often in rather open oi'der, so that the walls have 

 a transparent appearance. The oxea, which are small, usually about 90 m long and 

 never exceeding 160/x, are usually scarce, and in some specimens almost, if not entirely, 

 wanting. In the specimens with plentiful oxea there is a fringe round the oscule, 

 see Fig. 15, but in the specimens with few oxea there is little or no fringe. 



Spicules (Fig. 15). 



Oxea. — There are two sorts of oxea, ordinary and refringent : — 

 («) Ordinary oxea, straight or slightly curved, with a lance head which is 

 usually bent slightly to one side, GOm to KJOm long X :i m to C) fx thick. 



