304 PLATE LXXXVIl. 



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

 a tbin coating of Hymeniacidoii ladea. On tbe 5tb 

 February, 1873, I fortunately obtained from Miss 

 Oliver, a dealer in objects of natural History at 

 Hastings, a fresb specimen of tbe species very nearly 

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

 tunately witbout any spongeous envelopment. WTien 

 in tbe fresb condition it was of a dark purple colour, 

 very soft to tbe toucb, and it sbed an abundance of 

 fluid scarcode. In tbe living state tbe 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. 



Htmidesmia indistincta, BowerbanJc. 

 Plate LXXXVIl. 



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- 

 auchorate, and dentato - palmate equi - anchorate. 

 Skeleton. — Fasciculi loosely and irregidarly 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. 



