16 C. F. JENKIN. 



Spicules (Fig. 40). 



The Triradiates are of one sort : — 



(a) Approximately regular triradiates. Eays straight, tapering, rather bluntly 

 pointed, 130 ,« to 310 m long x 10 /x to 20 m thick. One of the rays is 

 occasionally rather longer than the other two, the maximum ratio observed 

 being 5/4. Very rarely one of the rays is shorter than the other two, the 

 maximum ratio observed being 3/2. The angles in all cases are almost 

 exactly equal ; r forms are occasionally found. 



The rare Quadriradiates are of two sorts : — - 



(6) Approximately regular quadriradiates from the lining of the excurrent 

 canals and gastral cavities. Facial rays straight, slender, slightly 

 tapering, bluntly pointed, 160 /^ to 200m long x 9m to 12 m thick. Angles 

 equal, 120°. Apical rays slender, wavy, sharply pointed, 280 m long x 8m 

 to 9 M thick, 

 (c) Abnormal quadriradiates apparently due to the growth of a very short 

 apical ray on one of type {a) triradiates. 



Leucandra brumalis. 

 (Plate XXX., Figs. 41-43.) 



There are five specimens of this new species in the collection. They have no very 

 definite shape (see Figs. 41 and 42), but all are considerably longer than they are 

 broad, and each has a single small gastral cavity, surrounded at the upper end by a 

 small membranous collar about 2*5 mm. long. They are smooth and white as 

 preserved in alcohol. The consistency of the sponge is fairly solid. 



Canal System. — There are small incurrent chambers under the dermis, 

 communicating with irregular, more or less radial, incurrent canals. The excurrent 

 canals are also more or less radial, opening into the gastral cavity. 



The Skeleton consists of slender regular triradiates with a few regular 

 quadriradiates round the gastral cavity. The apical rays, which project into the 

 gastral cavity, are very slender and crooked, the point being usually bent rather 

 sharply. 



This species resembles Leucaltis pumila, var. Bleekii (H), but the triradiates are 

 much smaller and slenderer, while the quadriradiates are regular instead of irregular. 



Spicules (Fig. 43). 



The Triradiates are of one sort :— 



(a) Eegular triradiates, rays straight, tapering uniformly to a fairly sharp point, 

 170 /A to 180 ju, long X 6/x to 10/u, thick. 



