338 A MONOGRAPH OF THE 



species; he obtained it during his deep sea dredging at 

 Shetland. The specimen is a small, irregularly ovoid, 

 tuberous mass, about half an inch in length, having an 

 even surface, with numerous small oscula irregularly dis- 

 persed. 



The Rev. A. M. Norman subsequently sent me nearly 

 two dozen specimens of this species. The general form 

 was nearly globular, or more or less oval. They varied in 

 size from about that of a walnut to a large pea, and the 

 colour of the dried specimens was uniformly a nut-brown. 

 The tension spicula of the dermal membrane are very 

 numerous, and are frequently so obtusely terminated at 

 the apex as to be readily mistaken for cylindrical spicula 

 by a hasty observer ; they are generally irregularly dis- 

 persed, but are occasionally collected into loose, flat 

 fasciculi ; they are not spinous. The skeleton spicula are 

 rather short and stout j they are profusely furnished with 

 small, short, conical spines, especially at the base, while 

 near the extreme apex they are frequently absent for the 

 length of from once to twice the greatest diameter of the 

 spiculum. 



One of the most striking structural characters of this 

 sponge is the profusion and large size of the anchorate 

 spicula with which the inner surface of the dermal and both 

 surfaces of the interstitial membranes are furnished. They 

 are unequally dispersed over those membranes ; in all parts 

 they are abundant, and in some spots they are crowded 

 closely together in great profusion. They vary greatly 

 in size. In some of the smaller ones indications of the 

 fimbriation of the shaft of the spiculum may frequently be 

 observed ; but in the larger forms it is strikingly visible by 

 the aid of a microscopic power of about 150 linear. The 

 pairs of fimbriae on the sides of the shaft extend in length 

 from near their distal terminations to within a short 

 distance of the middle of its bow, always leaving a space 

 of that portion of it, equal to about one fifth of its entire 

 length, without fimbriation. In a fully developed 

 spiculum, the lateral expansion of the fimbriae is often to 

 such an extent, that each considerably exceeds the 



