346 ' ECHINODERMATA. 
observe two ramified organs which may serve for respiration. The 
ova are contained in an oblong sac opening near the base of the pro- 
boscis. The Bonelliz live at a considerable depth in sand, extend- 
ing their proboscis to the water and even to the air above its surface 
when the tide is low. 
B. viridis, Rol., Acad. of Tur., X XVI, pl. xiv. It inhabits 
the Mediterranean(1). 
THALASSEMA, Cuv. 
Where the body is oval or oblong and :the proboscis in the form of 
a doubled lamina or bowl of a spoon, but not forked. The intestinal 
canal resembles that of the Bonelliz. They have but one abdominal 
thread. 
The Thalasseme are divided into 
/ 
THALASSEMA, proper, 
Where these two hooks are placed far forwards, and the posterior 
extremity is destitute of sete(2); and 
ECHIURUS, 
Where the posterior extremity is furnished with transverse ranges 
of sete. 
E. vulgaris; Lumbricus echiurus, Gm.; Pall., Miscel. Zool., 
XI, 1—6. Found along the coast of France in sandy bottoms. 
It is used as bait by fishermen. 
(1) In Rolando’s description, the mouth is converted into the anus, and vice 
versa. 
(2) Thalassema Neptuni, Gert., or Lumbricus thalassema, Pall. Spicil. Zool., 
fasc. X, tab. I, fig. 6;—Thalassema mutatorium, Montag., Lin. Trans., XI, v, 26, 
may not differ from the preceding one. : 
