324 A MONOGRAPH OF THE 



Two specimens of this sponge were found by Mr. Alder 

 on the shore at Bamborough. They were each of them 

 spread irregularly over a surface of about two square 

 inches, on no part exceeding two lines in thickness, and 

 were based on a portion of the root of a large Fucus, 

 covering and obscuring several species of Lepralia. Mr. 

 Alder described the sponge in his note as " of a faint 

 reddish colour when fresh ;" he also described it as con- 

 taining much gelatinous substance, and continued, " the 

 surface is hispid, and under the microscope the fibres can 

 scarcely be seen for granular matter imbedded in the sub- 

 stance." 



The primary lines of spicula are distinctly and strongly 

 developed in the skeleton of this species, and the secondary 

 ones equally distinct and very regular, producing a well- 

 marked scalariform appearance in the skeleton. The sur- 

 face characters of the sponge appear frequently to be more 

 or less modified by the Lepralia living beneath it, and it 

 then assumes an open porous character ; but when unin- 

 fluenced by such causes it is much closer in its texture, 

 and is profusely and regularly hispid by the projection of 

 the distal terminations of the primary lines of the skeleton. 

 The oscula are few in number, irregularly dispersed, and 

 are large for so thin a sponge ; in some cases being a Une in 

 diameter, and occasionally being slightly elevated above the 

 general surface. The dermal membrane at the base of the 

 projecting spicula is pellucid, and is perforated by nume- 

 rous minute pores ; the bicuspid anchorate spicula with 

 which it is furnished are irregularly dispersed and are 

 rather numerous. The interstitial membranes are thin 

 and transparent, and are occasionally coated with minute 

 granules ; they are furnished rather sparingly vnth slender 

 acuate, and very rarely, acerate spicula, and it is also rather 

 abundantly supplied with minute bicuspid-anchorate spicula 

 which require a power of about 250 linear to render them 

 readily visible. In a portion of the specimen kindly pre- 

 sented to me by my friend, Mr. Alder, the sarcode, when 

 examined in water, was very abundant, filling the whole of 

 the interstitial cavities in the form of a very minutely 



