192 BRITISH SPONGES 



7. HALISARCA,* Dujardin. 



Character. Substance fleshy or rather gelatinous^ 

 semitransparent, unorganized, forming an irregular crust 

 on the objects to which it adheres. 



1. H. DujARDiNii. Plate XVI. Fig, 8. 

 Halisarca, Dujardin in Ann. des. Sc. Nat. n. s. x, 7, pi. 1, fig. 5. 



Hab. On the under side of stones between tide-marks, and 

 on the stalk and roots of Laminaria digitata, common. Berwick 

 Bay : Holy Island, G. J. 



Sponge in the form of a gelatinous crust, spreading irregu- 

 larly, about a line in thickness, the surface even and smooth, of 

 a straw or ochre-yellow colour, mottled wdth little pale circular 

 spots or pores, produced apparently by a deficiency of colouring 

 matter in their places. A few of these transparent spots are 

 larger than the others ; and, if the fonner have any relation to 

 the pores of the true sponges, the latter may be the analogues of 

 the fecal oi'ifices. 



This production is liable to be mistaken for one of the crus- 

 taceous compound Tunicata, or rather for the gelatinous spawn 



* From stA./or, marine, and a-a^^, flesh. 



