EXPLANATION OF PLATES. 835 



granules are seen ; a, a, filaments. B, cell a more highly magni- 

 fied, with the filament everted; c, filament lying in the cell 

 rolled in a spiral. 



PLATE IV. ECHINODERMS. 



All the figures of this plate are taken from specimens in the Rijks- 

 Museum of Nat. History at Leyden. 



Fig. 1. Ophiolepis iw&Hcata MUELL. et TROSCH., p. 147, 1^ the nat. size, 

 seen from the under surface. To save space, the basal pieces 

 alone of four of the arms are delineated ; a, a, fissures near the 

 arms. 



Fig. 2. Under surface of a ray from a Japanese species of Astropecten, 

 p. 148, nat. size. Two rows of tentacula are seen here. 



Fig. 3. Oreaster Mulcus MUELL. et TROSCH., p. 149, seen from above, of 

 nat. size j the left side is in great part removed, a, anus ; b, 

 Madrepore-plate (verruca dor si); compare p. 148. 



Fig. 4. A ray of the same species opened, a, Sand-canal or stone 

 canal; see p. 148. 



Fig. 5. Under surface of part of a ray of Asterias (Asteracanthion) 

 rubens, p. 149, nat. size. Four rows of tentacles are seen; 

 see p. 149. 



Fig. 6. Spatangus purpureus, p. 152, seen from above, reduced one half. 

 There are four apertures of the genital organs (ovaria and testes} 

 and four circumscribed ambulacra. 



Fig. 7. Cidaris imperialis LAM., p. 156, after a specimen from the Red 

 Sea. The spines have been removed in order that the form of 

 the shell and the tubercles on which these spines are implanted 

 might be shewn. There are five sexual apertures round the 

 vent, on the same number of small pentangular plates of which 

 the hindmost is the largest : between them are the five eye- 

 plates. The am bulacra here run quite through. Compare pp.150, 

 151. 



Fig. 8. A spine of Cidarites glandiferus, or so-named pierre juda'ique, 

 fossil from the Jura formation. 



PLATE V. Fig. 1, ECHINODERMS ; figs. 27, INTESTINAL WORMS ; 

 figs. 8, 9, ROTIFERS. 



Fig. 1. Sipunculus nudus, p. 160, after GRUBE in MUELLER'S Archiv. 

 Fig. 2. Ccenurus cerebralis, p. 182, after BREMSER Icones helminth. A 

 part of the common bladder, with two worms highly magnified. 

 Fig. 3. Cysticercus longicollis, p. 182, magnified ; after the same, ibid. 



532 



