776 MR. A. G. THACKER ON [Juiie 16, 



quaclriracliates, large and small oxea, and minute grapnel-like 

 oxea. 



Colour (in alcohol) white. 



Distribution. Bermnda (Polejaef) ; Cape Yerde Islands {Cross- 

 land Collection). 



Leucandra sericata (Ridley). 



Synonymy : — 



Aph'oceras sericatum Ridley [20]. 



Leuconia se7ncatiim Breitfuss [8] [6]. 



Mr. Crossland collected two specimens of this species. One of 

 these is a solitary pear-shaped Leucon j)erson 11 mm. high and 

 with a maximum width of 5 mm. ; the other specimen consists of 

 three Leucon persons united at a common base, the central and 

 largest of the three individuals being 2 cm. high and having a 

 maximum width of 8 mm. The terminal oscula are protected by 

 well-developed oscular fringes ; the osculum of the largest indi- 

 vidual is 2-5 mm. in diameter. The scattered flagellate chambers 

 are usually somewhat elongated, occasionally being four times as 

 long as broad ; their width varies very little and is about 0"045 mm. 

 The primary inciu^rent canals have a diameter of 0*2 mm. and the 

 ultimate excurrent canals are about the same size. 



The Skeleton agrees with the description given by Ridley. 

 Many of the spicules of the gastral cortex lack apical rays, and 

 are therefore of course triradiates. 



Colour (in alcohol). One specimen is dirty white and the other 

 brown. 



Distribution. S.E. coast of Brazil {Ridley) ; Straits of Magellan 

 {Breitfuss); Cape Verde Islands {Crossland Collection). 



There is no doubt that this sponge is very closely allied to the 

 much commoner species, L. asjiera. It is to be distinguished from 

 the latter however, (1) by the inferior ratio of the thickness of 

 the large oxea to that of the parenchymal triradiates, and (2) by 

 the size and shape of these trii'adiates themselves, which are larger 

 than the corresponding spicules in L. aspera and are constantly 

 sagittal. The presence in L. sericata of an oscular crown composed 

 of special oxeotes, which is given by Ridley as a difference between 

 the tw~o forms, is a distinction which will not hold good, as this 

 structure also occurs in many specimens of L. aspera. 



Leucandra typica (PolejaefF). 

 Synonymy : — 



Leuconia typica, var. massa Polejaeff [19]. 

 ,, ,, var. tioha PolejaefF [19]. 



Leucandra typica, var. tuba Lendenfeld [18]. 



Leucandra typica Dendy [10]. 



Leuconia typica Breitfuss [6]. 



Mr. Crossland dredged five specimens of this widely distri- 

 buted species. One specimen consists of a mass of very wide, 

 very short, united Leucon persons, and therefore is of the shape 



