Part first. 



Tank No. 1. 



Containing exclusively Echinoderms (p. 72). 



1. Starfishes or "five-fingers", with five (rarely more) creeping 



arms: Echinaster (fig. 2), red and slender armed; Luidia (fig. 5) 

 orange, and much larger; generally with seven arms; Asterias 

 (fig. 3), large and greenish or brownish, with pointed knobs; 

 Astropecten (fig. i), with points like little tusks fringing the arms ; 

 Palmipes, arms webbed, like a pentagonal piece of red paper. 



2. Brittle-stars, with five (or rarely six) arms, thinner and more 



snake-like than those of the Starfishes; round body like a 

 thick halfpenny {Ophioderma, fig. 4). 



3 . Feather-stars, {A ntedon, fig. 6) mostly holdingby their backs to dead 



coral-stems (see tank 2 1 ) in the centre of the tank. They are yellow 

 or red and have ten plumed arms with which they can swim. 



4. Sea-urchins, globular or base-shaped and covered with spines. 



Sphaerechinus (fig. 8), generally purplish, the spines being 

 tipped with white; Strongylocentrotus, smaller and more de- 

 pressed, of a very dark purple colour, largely eaten in Naples ; 

 Dorocidaris (fig. 7), pink with knobs, bearing a few long and 

 sticklike spines. Several other kinds. 



5. Sea-cucumbers, sack-shaped bodies covered with suckers. The 



delicate brown feathery undergrowth will be seen to be the 

 tentacles of numerous sea-cucumbers {Cucumaria, fig. 9), ad- 

 hering to the rocks; each has ten tentacles round its mouth, 

 in crawling they are retracted; in the larger species {Holo- 

 thuria, fig. 11) which is black, they are not obvious; Stichopus 

 (fig. 10) is reddish, a foot long, and flat. 

 The starfishes, sea-urchins and sea-cucumbers adhere to the 

 glass or rock by numerous suckers, with which they crawl (for 

 details v. p. 72); the brittle-stars move by wriggling, the feather- 

 stars can swim by movements of their arms. 



Fig. I. Astropecten aurantiaais, 

 V4 nat. size. p. 75. 



Fig. 2. Echinaster seposifus, 

 1/3 nat. size. p. 75- 



