8 PLATE III. 



Fig. 9. One of the spiculated, equiangular, tri- 

 radiate, internal, defensive spicula of L. contorta. X 

 150 linear. 



Fig. 10. One of the procumbent, acerate, spicula 

 of the exterior surface of L. contorta. X 150 linear. 



LEUCOSOLEXIA COEIACEA, Boiverbank. 



Vol. ii, p. 34, ' Mon. Brit. Spongiadse.' 



Fig. 11. A specimen of L. coriacea from the Guliot 

 Caves, Sark. Natural size. 



Fig. 12. A second specimen of L. coriacea from the 

 Guliot Caves, exhibiting the tortuous fistulas of the 

 sponge. Natural size. 



Fig. 13. A magnified view of a portion of the 

 surface of the specimen represented by fig. 12. 

 X 12 linear. 



Fig. 14. One of the skeleton spicula of L. coriacea. 

 X 123 linear. 



After the plate containing the illustration of L. 

 coriacea was printed, I found a specimen of that sponge 

 preserved in spirit with several other small specimens 

 from Shetland, which were sent to me for examina- 

 tion by the Rev. A. M. Norman. On examining it 

 microscopically I found it contained an abundance of 

 gemmules. They were exceedingly numerous on the 

 inner surface of the dermal membrane. Their form 

 was either spherical or slightly oval ; they were of a 

 nut-brown colour, and filled with numerous spherical 

 molecules, which were distinctly visible with a power 

 of 700 linear. One of the largest of the gemmules 

 measured 11 1 19 inch" in diameter, and the molecules 

 within it did not exceed 15 Q 00 inch in diameter. This 

 gemmule had all the appearance of being in a fully 

 developed condition. The greater portion of the other 

 gemmules were much smaller ; one of about the average 

 size measured YTo~5 inch in diameter. 



