PLATE XXXI. 79 



Torbay, collected by Mr. Gosse. Fig. 8 represents the 

 branching variety. Occasionally, but very rarely, 

 there are as many as three branches. Natural size. 



Fig. 10. One of the large fusiformi-acerate spicula 

 of the skeleton. X 150 linear. 



HYMENIACIDON PERARMATUS, Bowerbank. 



Vol. ii, p. 164, ' Mon. Brit. Spongiacte.' 



Fig. 11. Represents the type-specimen in the col- 

 lection of the Rev. A. M. Norman of the natural size. 

 The front of the stone is covered by the sponge, ex- 

 cepting the angular space at (a). At nearly the middle 

 of the sponge a few of the slightly elevated oscula are 

 apparent as represented. 



Figs. 12, 13. --Two of the large, acerate, skeleton 

 spicula. X 150 linear. 



Figs. 14, 15. Two of the equianchorate, tridentate, 

 retentive spicula, X 320 linear, representing about the 

 largest and the smallest of these spicula. 



Fig. 16. An average-sized, attenuate- clavate, en- 

 tirely- spined, internal, defensive spiculum. X 150 

 linear. They vary much in size, some being nearly 

 twice the length of the one figured, while others are 

 not above half the length of the figured one. 



