PLATE I. 



GRANTIA COMPRESSA, Fleming. 



Vol. ii, p. 17, ' Mon. Brit. Spongiadse,' and vol. i, pi. xxi, figs. 312 314. 



Fig. 1. A group of three fine specimens from near 

 the hard at Waltou-on-the-Naze figured in the con- 

 dition in which they came from the sea. Natural 

 size. 



Figs. 2, 3, 4, 5.- -Varieties of form from the rocks 

 forming the sides of the great cavern of St. Katherine's 

 Island, Tenby, figured in the condition in which they 

 came from the sea. Natural size. 



Fig. 6. Specimens parasitical on a fucus from the 

 Guliot Caves, Island of Sark, from a dried specimen. 

 Natural size. 



Fig. 7. An equiangular triradiate skeleton spiculum 

 from the side of one of the large cells of the sponge. 

 X 150 linear. 



Fig. 8. An elongo-equiangulated triradiate skeleton 

 spiculum from the partial division in the middle of 

 one of the large skeleton cells. X 150 linear. 



Figs. 9 and 10. --Two of the spiculated triradiate 

 defensive spicula from the sides of the cloaca ; No. 



9 with the defensive ray passing from the eye, and No. 



10 with the defensive ray projected towards the eye. 

 X 150 linear. 



Figs. 11 and 12.- -Two of the flecto-clavate external 

 defensive spicula of the sponge; No. 11 the normal 

 form, No. 12 an extreme variation. X 150 linear. 



The sinuous line occupying a large space in the plate 

 represents the form and size of the largest known 

 specimen, from the River Orwell, described in page 18, 

 vol. ii, ' Mon. Brit. Spongiadas.' 



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