REMARKABLE MARINE INVERTEBRATA NEW TO THE BRITISH SEAS. 315 
EXPLANATION OF THE PLATES. 

PLATE IX. 
ig. 1. Holothuria intestinalis, natural size. 
. 2a, Arachnactis albida, natural size; and 26. the same with some of the outer tentacula 
removed in order to shew the inner circle and the globular form at times assumed by the body. 
. 8a, Sarcodictyon agglomerata, natural size; 3b. the same magnified ; and 3. the polypes. 
Fig. 4a. Syntethys hebridicus, less than the natural size; 46. one of the individual Ascidians of 
the size of nature; 4c. the same with the inner tunic retracted ; 4 d. the orifices of the inner 
and outer tunics much magnified. 
PLATE X. 
. la, Plancia gracilis, three times the natural size, seen in profile; 1. the same, seen from 
above; lc. its peduncle; 1 d. orifice of the peduncle; 1 e. extremity of a tentacle. 
ig. 2a. Oceania ducalis, much magnified, and seen in profile; 2. the peduncle, ovaries, and 
mouth ; 2c. one of its tentacula. 
Fig. 3. Slabberia catenata, natural size; 3b. the same, magnified ; 3c. its peduncle; 3d. genital 
glands on the side of a gastro-vascular canal; 3 e. one of the tentacula, 
‘Fig. 4a. Natural size of Hippocrene pyramidata; 4 b. the same, magnified; 4 c. as seen from above ; 
4 d. the genital lobes and peduncle; 4 ¢. genital cross; 4/7. one of the tentacular fascicles. 
Fig. 5 a. Natural size of Hippocrene cruciata; 5b. lateral view, magnified ; 5c. view from above: 
Fg PP gn: 
5 d. genital lobes and peduncle ; 5 ¢. one of the tentacular fascicles. 
‘Fig. 6 a. Natural size of Hippocrene simplex ; 6 b. lateral view magnified; 6c. the view from below ; 
6 d. one of the tentacular fascicles ; 6 e. genital lobes and peduncle. 
y. 7 a. Thaumantias, natural size; 7 b. diagram of same, seen from above; 7c. section shewing 
the genital folds and stomach ; 7 d. margin and tentacula. 
. 8a. Thaumantias confluens, side view magnified ; 8 b. diagram of view from above; 8c. pe- 
duncle and buccal lobes ; 8 d. margin and tentacula. 
me) VOL. XX. PART It. 4Q 
