36 A MONOGRAPH OF THE 



probably be also the case in L. coriacea, which in the 

 structure of its parieties very closely resembles those of 

 L. contorta. 



Montagu's description of his Spongia coriacea applies 

 very much more correctly to a small specimen of Baphyrus 

 Grifflthsii of this work than to the calcareous species de- 

 scribed above. 



This sponge has been found as far north as Davis's 

 Straits by Dr. Walker, who presented a specimen of it to 

 Professor Dickie of Queen's College, Belfast, from whom I 

 received it for examination in the autumn of 1858. The 

 specimen differed in no respect from those which I have 

 received from Guernsey. 



Genus — Leuconia, Grant. 



1. Leuconia nivea, Bowerbank. 



2. — fistulosa, Bowerbank. 



3. — pumila, Bowerbank. 



1. Leuconia NivEA, 5oioer5a«£ 



Gkantia NiVBA, Fleming. 

 — — Johnston. 



Sponge. Sessile, massive or coating; surface lobular or 

 crested, smooth. Cloacae numerous, mouths simple, 

 armed internally with very large and stout equiangular 

 spiculated triradiate spicula, radii attenuated. Mem- 

 brane of cloaca furnished abundantly with unicurvo- 

 cruciform spicula. Oscula numerous, simple, dis- 

 persed over the surfaces of the cloacae. Pores minute. 

 Spicula of skeleton equiangular trjradiate, very variable 

 in size and stoutness. Spicula of interstitial and 

 dermal membrane small, acerate; and minute attenuato- 

 spiculated triradiate spicula ; spicular ray short, basal 

 rays tripodate. 



