110 BRITISH SPONGES: 



not easily compressed, non-elastic, the surface even and porous, 

 the interior irregularly cellular like crumb-of-bread, and friable 

 when dried. The spicula lie in their subcorneous membrane 

 crossed in every direction : they are short, stout, smooth, curved, 

 cylindric with sharp extremities, and are nearly all of the same 

 size and form. They are not unlike those of H. oculata but 

 more curved. 



The var. /3. has a very peculiar mode of growth. Rising from 

 its original site in the form of a knob, it extends laterally until 

 the branch meets with an elevation on the rock to which it also 

 roots itself; and thus it spreads, from point to point, until the 

 sponge rests on knobs placed at irregular intervals, like the pil- 

 lars of some rude I'ustic bridge, their number and position being 

 apparently determined by the inequalities of the place of growth. 

 A specimen of this kind somewhat resembles a small knobbed 

 stick in a rottened condition. When the primary knob continues 

 solitary we have the nipple-like variety, which, fixed by a spread 

 base, rises to about an inch in height, having an enlarged roimd- 

 ed apex more widely porous than the stalk, and perforated with 

 a single osculum. 



H. simulanshas an evident affinity with the Alcionio fora- 

 MINOSO of Iirqyerato, Hist. Nat. p. 641 ; but it isnot the Spongia 

 rubens of Pallas, nor the Sp. nodosa of Linnaeus. Spokgia 

 CLAVATA o{ Esper, Spong. tab. 19, seems also related, both in 

 texture and habit, to H. simulans. 



" Forma Spongiarum infinite variat et in eadem saepe specie 

 adeo diversa observatur, ut vix agnosceres, nisi substantia, tex- 

 tura, intermediaeque varietates facem praeferrent." Pallas. 



13. H. CINEREA, crustaccous, spongy, blackish-grey, unpo- 

 rous, the oscula feio and obscure ; spicula linear, curved, 

 pointed at both ends. 



