36 BRITISH Tl'NICATA. 



nerves. Branchial aperture with six sharply-pointed 

 lobes. Thorax and abdomen saffron-yellow in colour, 

 united by a peduncle a little longer than the thorax. 

 Stomach nearly globular, very simple, the intestine 

 with two slight constrictions below the stomach before 

 its upward, ventral bend. 



Diameter of mass one inch to two inches (25 to 

 50 mm.). Length of individuals half a line (1 mm.). 



Hull. Investing Madrepores. 



ENGLAND. Scilty Islands (C-arvs). 

 /'V/'x/ record. -Cams, 1850. 



This species is admitted on the authority of Victor 

 Cams as the fact of its having been found in the Gulf 

 of Suez does not seem a sufficient reason for doubting' 

 its occurrence in British waters. 



Fi. 104. Didemnmn cainliil nni. Natural size 1 . (Savigny, pi. iv, f. 3.) 



Savigny describes it as being opaque, fungous, or 

 spongeous, spreading over and more or less enveloping 

 the steins of madrepores in milk-white incrustations, 

 its surface covered with prominent nipples arranged 

 in six rays and disposed nearly in quincunx. The 

 individuals, or polypes as he calls them, are, he says, 

 yellow and very small, scarcely equalling in volume 

 two poppy seeds, one for the thorax, the other for the 

 abdomen and ovary together. The branchial aperture 

 resembles a funnel with its limb or upper margin cut 

 out into six very simple teeth, which are expanded 

 and pointed. The thorax is short, rounded, and 

 furrowed transversely, the back very gibbous and 

 divided by a longitudinal depression, the front 

 hollowed out below the tubercle. The abdomen is 

 larger than the thorax and nearly horizontal in 





