46 
ZOOLOGY. 
is sold for soups in Chinese markets. Our native com- 
monest species is Pentada frondosa (Fig. 48). 
Fig. 48.— Common Sea-cucumber, with the gills nearly expanded. After Em- 
erton. 
Literature. 
O, J. Romanes. Jelly-fish, Star-fish, and Sea-urchins, 1885. 
J, Muller. Seven Memoirs on the Larvj3e and Development of 
Echinoderms. Berlin, 1846-54. 
A, Agassiz. Embryology of the Star-fish, 1864. 
E. Metschnikoff. Studien liber die Entvrickelungsgeschichte der 
Echinodermen und Nemertinen. St. Petersburg, 1869. 
H. Ludwig. Morphologische Studien an Echinodermen. Leip- 
zig, 1877-78. 
