304 PLATE LXXXVIL 



visible, as the greater part of its surface is covered by 

 a thin coating of Hymeniacidon lactea. On the 5th 

 February, 1873, I fortunately obtained from Miss 

 Oliver, a dealer in objects of natural history at 

 Hastings, a fresh specimen of the species very nearly 

 enveloping a small crab, probably Pisa Gilbsii, and for- 

 tunately without any spongeous envelopment. When 

 in the fresh condition it was of a dark purple colour, 

 very soft to the touch, and it shed an abundance of 

 fluid scarcode. In the living state the surface was 

 quite smooth in appearance, but as it dried it became 

 rough and uneven, and it retained its dark purple 

 colour. In all its structural characters it was in per- 

 fect accordance with those of the type-specimen. 



HYMIDESMIA INDISTINCTA, Bowerlanlc. 

 Plate LXXXVII. 



Sponge coating, surface smooth, rather uneven. 

 Oscula simple, minute, dispersed. Pores inconspicuous. 

 Dermal membrane spiculous ; tension spicula acerate, 

 long and slender, abruptly pointed, dispersed, or 

 loosely fasciculated ; retentive spicula ; bidentate equi- 

 anchorate, and dentato - palmate equi - anchorate. 

 Skeleton. Fasciculi loosely and irregularly con- 

 structed ; frequently composed of not more than two 

 or three spicula, irregularly disposed. Spicula at- 

 tenuato-acuate, long and slender, variable in size; 

 basally, incipiently spinous. Basal membrane abun- 

 dantly furnished with cylindrical entirely spined ten- 

 sion spicula, fasciculated or dispersed singly, rather 

 stout and large ; and also with numerous internal 

 defensive spicula, acuate, entirely but incipiently 

 spinous ; retentive spicula same as those of the dermal 

 membrane. 



Colour. Light brown in the dried state. 



Habitat. Shetland; Rev. A. M. Norman. 



Examined, In the dried state. 



