178 A MONOGRAPH OF THE 



characters will generally serve to distinguish the one from 

 the other, and among the structural characters the marked 

 difference that exists between the dermal membranes and 

 their associated spicula, and the absence of granulation in 

 the dermal and other membranes of II. fallax, will aid es- 

 sentially in the separation of the two species. 



I am indebted to the late Mrs. Griffiths, of Torquay, for 

 this sponge. She obtained it from one of the trawlers, and 

 it was probably from Torbay. 



IS.Hymeniacidon viridans, Bowerbank. 



Sponge. Coating ; surface even, minutely corrugated, 

 slightly hispid. Oscula slightly elevated and mar- 

 gined, dispersed. Pores inconspicuous, congregated. 

 Dermal membrane spiculous ; spicula abundant, same 

 as those of the skeleton, dispersed or sub-fasciculated. 

 Skeleton. Spicula acuate, moderately stout. Tension 

 spicula acuate, slender, as long as those of the skele- 

 ton. Gemmules spherical, membranous, aspiculous. 



Colour. Alive, red tinted with green ; dried, green ex- 

 ternally, buff yellow internally. 



Habitat. Ban try Bay, Rev. A. M. Norman. 

 Examined. In the dried state. 



I am indebted to the Rev. A. M. Norman for my know- 

 ledge of this species, He sent me for examination a 

 single specimen in excellent preservation, two and a half 

 inches long, two inches wide, and about four and a half 

 lines in thickness, the external colour being a rather pale 

 but vivid green. The surface was even, but minutely and 

 strikingly corrugated, in the dried sponge ; but in the 

 living condition it is probable that the surface would be 

 nearly, if not entirely, free from the corrugations. When 

 a slice from the dermal surface was examined in a little 

 water, with a power of 100 linear, the elevated portions 

 of the corrugations were found to be most abundantly spi- 

 culous. while the depressed parts were each occupied by 



