| bli ae a laa 
Mr. W. S. Kent on two new Siliceous Sponges. 223 
Affinities of the described Species. 
teristic of the Tethyade), falls naturally into the family 
Esperiade of the Armatospongie of Dr. Gray. The cha- 
system, further demand its generic separation. I would, 
ved for the 
arding the new genus ZYeldíing?a, in the present limited 
state of our knowledge of the Coralliospongise, it seems. dif- 
ficult to establish any immediate bonds of affinity. Thionella 
Dr. J. E. Gray, Proc. Zool. Soc. 1868), however, in the more 
massive character of its cortical layer, and in its internal reti- , 
culated structure, indicates a distant resemblance, yet closer 
than is to be found in either Habrodictyon, Hyalonema, Eu- 
plectella, Aphrocallistes, Dactylocalyx, Farrea, Macandrewia, 
. or Pheronema (Holtenia, W yv. Thomson), the remaining ge- 
nera of the order with which we are at present conversant. 
EXPLANATION OF PLATE XV. 
Fig. 1. Rhaphidotheca Marshall- Hallii, nat. size, adherent to a piece of 
: Lophohelia prolifera. 
Fig. 2. A section of the same, showing the vaulted internal structure, 
