200 DESCRIPTION OF THE PLATES. 
Prate Y. 
Fig. 1. Spicules of Thyone fusus, the two lower x 450 to show the 
details of those figured on their right (p. 42). 
Fig. 2. Spicules of Thyone raphanus (p. 42). 
Fig. 3. 9 Phyllophorus pellucidus (p. 46). 
Fig. 4 5; 55 drummondi (p. 47). 
Prate VI. 
Fig. 1. Spicules of Psolus phantapus (p. 44). 
Fig. 2 »  fabricii: a, from the body-wall ; 6, from 
the podia (p. 45). 
Fig. 3. Spicules of Holothuria intestinalis (p. 48). 
Fig. 4. a 5 tremula (p. 49). 
Fig. 5 nigra (p. 49); the three uppermost 
x 450 to show the details of those which lie just below 
them. 
Pirate VII. 
Figures of external forms of Holothurians, from specimens 
preserved in spirit. 
Fig. 1. Synapta digitata, nat. size (p. 34). 
Fig. 2. Tentacles of Sz ynapta digitata, x 6, to show the arrange- 
ment of the pinne on the tentacles. 
Fig. 3. Thyone fusus, nat. size (p. 42). 
Fig. 4, Phyllophorus drummondi, nat. size (p. 47). 
Prats VIII. 
Figures of external forms of Holothurians; figs. 1, 2, and 5 from 
life, 3 and 4 from spirit-specimens. 
Fig. 1. Cucumaria plance, xe (p. 37). 
2. Cucumaria pentactes, X 3 (p. 37). 
Fig. 3. Thyone raphanus, X 2 (p. 42), 
4, Psolus phantapus, nat. size (p. 44). 
5 
. Holothuria nigra, x = (p. 49). 
Prats IX. 
Figures to illustrate the structure and variations of 
Antedon bifida (p. 54). 
Dorsal view of disk to show the cirrus-pits (cp), the modes 
of branching of the arms, the form of the radials (R°), 
and a syzygy (sz), x8. 
Fig. 1 
