236 A MONOGRAPH OF THE 



shape by the Fucus on which it is based and which it par- 

 tially envelops. A third specimen in the cabinet of Mr. 

 Bean of Scarborough, has enveloped several small stems of 

 a Zoophyte, and has thus assumed very much the size and 

 branched form of a small specimen of Dictyocylindrus 

 rugosus; six specimens dredged by the Rev. A. M. Norman, 

 at Guernsey, ranged from six lines in length to an inch 

 and a half. They were all parasitical on small Fuci, and 

 were irregularly massive in form. It therefore appears that 

 the species does not attain a great size. 



5. Halichondria inconspicua, Bowerbank. 



Sponge. Massive, sessile ; surface rugose. Oscula simple, 

 large. Pores inconspicuous, and not very numerous. 

 Dermal membrane pellucid ; spicula same as those of 

 the skeleton, numerous, usually dispersed, sometimes 

 fasciculated. Skeleton spicula acerate, stout, and rather 

 short, Tension spicula of the interstitial membranes, 

 acerate, slender. 



Colour. Dried, light gray. 

 Habitat. Tenby, Mrs. Brett. 

 Examined. In the dried state. 



I have seen but one specimen of this sponge. It is a 

 small mass nine lines in length, six in breadth and the 

 same in height ; the surface is nearly even, but somewhat 

 rugged. It has one large osculum which is simple and 

 irregular in form, its greatest diameter rather exceeded two 

 lines ; there were also two or three smaller ones, less than 

 a line in diameter. The pores are visible by the aid of an 

 inch lens. The greater part of the dermal spicula are 

 irregularly dispersed, but occasionally they are collected 

 into elongated fasciculi, simulating the appearance of frag- 

 ments of primary lines of an Isodictya ; but no such fasci- 

 culi appear in the mass of the sponge when a section at 

 right angles to its surface is examined. 



