18 C. F. JENKIN. 



The Skeleton is built up almost entirely of regular triradiates, but among the 

 triradiates lining the excurrent canals there are a very few regular quadriradiatcs with 

 slender, wavy, apical rays projecting inwards. 



The oscule is closed by the folding in of a thin oscular collar which, when open, 

 probably stands erect as a short tube. The collar has a thin skeleton of triradiates. 



Spicules (Fig. 50). 



The Triradiates are of one sort : 



(a) Regular triradiates of widely differing sizes. Rays almost perfectly straight, 



but not quite, tapering moderately to near their ends, then sharply pointed, 

 140 M to 320 M long X 10 n to 20 M thick. 



The rare Quadriradiates are of one sort : 



(b) Regular quadriradiates from the lining of the excurrent canals. Facial rays 



equal, straight, tapering moderately to near their ends, then sharply pointed, 

 110 M long x 8 M thick. Apical rays wavy, sharply pointed, 80 M to 100 M 

 long X 3 M to 8 M thick. 



LEUCANDRA CIRRATA. 

 (Plate XXXI., Figs. 54-56.) 



There are two specimens of this new species in the collection, one complete, the 

 other much distorted, and possibly only a portion of a complete sponge. The follow- 

 ing description applies to the complete specimen. The sponge is ovoid in shape, 

 8*5 mm. x 3 mm., and is white as preserved in spirits. It is completely covered by 

 long, angularly bent projecting oxea, which to the naked eye give the surface the 

 appearance of being covered with curling hair. 



The structure of the body wall which surrounds a large gastral cavity is shown in 

 Fig. 54. The gastral skeleton consists of triradiates and quadriradiates lying 

 tangentially with their basal ray downwards ; the body skeleton consists of sub- 

 gastral triradiates and the inner ends of the projecting oxea ; the dermal skeleton is 

 strong, consisting of about eight layers of triradiates, irregularly placed. The oxea 

 and sub-gastral triradiates are arranged in groups up which the body substance 

 (flagellated chambers) creeps to the dermis, forming as it were columns supporting the 

 cortex. Between these columns under the cortex is a large space forming an incurrent 

 chamber which is continuous over the whole sponge. 



There are only two or three layers of the flagellated chambers, which are roughly 

 spherical, between the gastral and dermal membranes. The excurrent canals are short 

 and simple. . 



The oscule has a fringe of stumpy oxea (Fig. 56) ; there is no diaphragm. 



