PLATE LXXIII. 205 



pellucid, spiculous ; spicula cylindrical, long, slender, 

 and very flexuous ; rarely acerate, irregularly dis- 

 persed, numerous. Basal membrane stout, abundantly 

 spiculous ; spicula like those of tlie dermal mem- 

 brane, very numerous, and closely matted together. 

 Skeleton, — Columns short and stout ; spicula acuate, 

 not more than half the length of those of the dermal 

 and basal membranes, but rather stouter. 



Colour. — Milk white in the dried state. 



Habitat. — Shetland, 96 fathoms j Rev. A. M. 

 Norman. 



Examined, — In the dried state. 



This specimen was dredged at Shetland in 1867. 

 It is a nearly circular flat patch of sponge five lines in 

 diameter, and its greatest thickness is about a line and 

 half. It has apparently been scraped ofi" a stone or an 

 old shell. The surface is very uneven and rugged, 

 apparently from the shrinking inward of the dermal 

 tissues, so that the distal extremities of the skeleton 

 columns are projected in the form of miniature 

 hillocks. 



The most remarkable character in this species is the 

 simplicity of its organization. The columnar structure 

 of the skeleton is very indistinctly produced. The 

 spicula of which it is composed are all acuate or sub- 

 attenuato-acuate, their divergence from the column is 

 at a very slight angle until they attain the surface 

 where they spread out and form an irregular plain of 

 support to the dermal membrane and its spicula. The 

 spicula of the dermal membrane are few in number 

 as compared with those of the basal one. They are 

 alike in every respect in the two membranes, and are 

 at least twice as long as those of the skeleton, and are 

 rather less in their diameter. In the basal membrane 

 they are very numerous, and are closely felted together. 

 A very few comparatively short acerate spicula are 

 occasionally found among them. No internal defensive 

 or retentive spicula could be detected in any part of 

 the sponge. 



