64 A MONOGRAPH OF THE 



1865. It agrees in all its essential characters with the type 

 specimen of the species. 



4. Polymastia brevis, Bowerbank. 



Sponge. Sessile, or slightly pedicelled, massively clavate, 

 short, somewhat compressed, consisting of a single 

 large fistula. Surface even, minutely but profusely 

 hisped. Oscula and pores inconspicuous. Dermal 

 membrane aspiculous. External defensive spicula 

 acerate, or snb-fusiformi-acerate, short, very numerous ; 

 projected at about right angles through the dermal 

 membrane for about one fifth of their length. Skele- 

 ton spicula. Super-fusiformi-acerate, large and long. 

 Interstitial membranes ; tension spicula, acerate, or 

 sub-fusiformi-acerate, short, numerous, frequently fas- 

 ciculated. 



Colour. Ochreous yellow, dried. Orange, when alive. 

 Habitat Shetland, 60 to 90 fathoms. Mr. Barlee, 

 Rev. Mr. Norman, Mr. Peach. 

 Examined. In the dried state. 



I received from my late friend, Mr. Barlee. eleven specimens 

 of this sponge. One was based on the shell of a living 

 vermetus, the remainder were on small pebbles. The basal 

 attachment exceeded in its diameter very little that of the 

 smallest part of the ascending column of the sponge, which 

 in most cases gradually increased in size, from the proximal 

 to the distal extremity, which in some, presented a hemi- 

 spherical form, while in others it assumed a compressed 

 and truncated appearance. The height of the sponges 

 varied from six to eight lines ; the base being about two 

 lines in diameter, and the distal extremity about three or 

 four lines. When divided longitudinally, the parietes of 

 the sponge did not exceed in the dried state, the fourth of 

 a line in thickness at any part, and the internal cavity 



