121 



PLATE XLVIII. 



ISODICTYA CINEREA, 



Vol. ii, p. 274, ' Mon. Brit. Spongiadse.' 



Fig. 1. Represents a specimen of the species in a 



fine state of preservation from Fowey, Cornwall, by 



Mr. C. W. Peach. Natural size. 



Fig. 2. One of the type-specimens of the species 



in the Johnstoiiiau collection in the British Museum 



marked 17. Natural size. 



Fig. 3. Another specimen of the species in the 



Johnstonian collection in the British Museum marked 



17 d . Natural size. 



Fig. 4. A skeleton spiculum, from the specimen 



represented by fig. 2. X 250 linear. 



Fig. 5. One of the tension spicula, from the inter- 

 stitial membranes of the specimen represented by fig. 2. 

 X 250 linear. 



I regret that I have been unable to figure the type- 

 specimen of this sponge. I applied to my friend 

 Professor Grant for the loan of it for that purpose, 

 but unfortunately, although diligently searched for, it 

 could not be found. When I wrote the description of 

 this sponge, in vol. ii, p. 275, of the ' Mon. Brit. 

 Spongiadse,' I believed it to be a rare species, but 

 since that time I have obtained numerous specimens 

 from various localities exhibiting considerable varia- 

 tions in form. Very few of them exceeded the figured 

 specimen, Plate XXXVII, fig. 1, in size; but since 

 then I have examined a specimen I obtained from the 

 Diamond Ground off Hastings that greatly exceeds any 

 of those previously acquired in its dimensions, and 

 which, unlike any of them, appears to have risen from 

 a sessile base and to have assumed a rudely compressed 

 fan- like form, two and three quarters inches high and 



