BRITISH SPONGIAD^. 



40. IsoDicTYA Barleei, Bowerbcmk. 



Sponge. Sessile, or slightly pedicelled; irregularly fan- 

 shaped, sometimes consisting of two or more foliations 

 from the same base; foliations thick and fleshy. 

 Sm-face even, Oscula simple, circular, about a line 

 in diameter; congregated in circular or radiating 

 groups, which are nearly equidistantly dispersed over 

 the external surfaces of the sponge. Pores conspi- 

 cuous, dispersed on the whole of the surface of the 

 sponge. Dermal membrane spiculous. Spicula acuate, 

 very slender, about as long as those of the skeleton, 

 abundant, and often sub-fasciculated. Skeleton. 

 Coarse and very difiFase ; primary and secondary lines 

 multispiculous. Spicula sub-flecto-acuate, short and 

 stout. Interstitial membranes. Tension-spicula same 

 as those of dermal membrane. 



Colour. — Alive, pale buff or yellow. 

 Habitat. — Haaf Banks, Shetland, Mr. Barlee and Mr. 

 Humphreys. 



Examined. — As from the sea, in salt and water pickle. 



A single sponge of this species was dredged at the Haaf 

 Banks, Shetland, by Mr. Barlee, in the year 1851, in from 

 60 to 90 fathoms. The natural base of the sponge was 

 not obtained. The torn base was about two inches long, 

 and from half an inch to an inch in thickness, so that pro- 

 bably the sponge may, when perfect, have had a short 

 pedicel. It consists of three fans or leaves, of irregular 

 sizes and proportions, and one of them, the tallest, is divided 

 near its distal termination into two smaller, or secondary 

 fans. The surface is nearly even, and the average thickness 

 of the sponge is about half an inch. 



The groups of oscula generally consist of a central one 

 with from five to eight others around it, usually disposed in 

 radiating lines. The groups are about equidistant from 



