DESCRIPTION OF THE PLATES. 
Plates I-VI. illustrate the spicules of Holothurians, magnified, 
unless otherwise stated, 290 times. Spicules for microscopic 
observation can be readily prepared by cutting off a podion or a 
small portion of the skin, and treating it with a few drops of 
caustic potash at a moderate heat. 
Fig. 
Fig. 
bo 
g9 bo ps 
Prats I. 
Anchors and plates of Synapta inherens (p. 33). 
bushi (p. 34). 
digitata (p. 34). 
”? 9 ” 
9 ” > 
Prate II. 
. a, Plates from the body-wall; and 6, Spicules from the 
podia of Cucumaria hyndmani (p. 36). 
. The same from Cucumaria planci; c, Spicules, x 450 
(p. 37). 
Prate ITI. 
. a, Plates from the body-wall; and 3, Spicules from the 
podia of Cucumaria pentactes (p. 37). 
. The same from Cucumaria lactea (p. 38). 
Pratt LY. 
. Spicules of Cucumaria hispida, shown as large as they are 
for the purpose of being easily compared with the 
others, as they are drawn to exactly the same scale as 
most (p. 38). 
. The same of C. frondosa; these generally become less nume- 
rous as the animal increases in size (p. 39). 
