1908.] 



CAPE VERDE ISLANDS SPONGES. 



761 



The large quadriradiates are also regular, have conical, fairly 

 sharply pointed rays, and are distributed without order in the 

 walls of the Ascon-tubes. The average length of their facial 

 rays is 0*2 mm., and the thickness of the same at their bases 

 is 0'035 mm. The apical rays are straight or slightly curved, 

 are sharply pointed, are usually about half as long as the 

 facial rays, and have a basal thickness of 0"025 mm. These 

 spicules are quite numerous and do not vary much in size. The 

 oxeote spicules are ari-anged transversely in the thickness of the 

 sponge-wall, and their outer ends, which are slightly bent, project 

 beyond the surface. They are fairly shai'ply pointed at both ends. 

 Their average length is 0'3 mm. and their maximum thickness 

 0*009 mm. They are cylindincal, do not vary much in size, and 

 are quite numerous. 



Text-fig. 156. 



Spicules from Leucosolenia atlantica. 



a = Triradiates. h = Small quadriradiates. c = Large quadriradiates. 

 d = Oxeotes. All X 120. 



A few very fine hair-like, but not very long oxea are to be 

 found in parts of the sponge. These are very probably young- 

 forms, but even if this is not the case I do not think they are to 

 be considered of much systematic valvie. 



This species appears to be more closely allied to Leucosolenia 

 laxa Kirk [15], than to any other previously described Ascon. 

 It is distinguished, however, from the New Zealand form (1) by 

 having the quadriradiates difierentiated into spicules of two 

 distinct sizes, (2) by having oxea considerably thinner than those 

 of L. laxa, and (3) by its looser external form. 



Distribution. CapeYerde Islands {Crossland Collection). 



