ROSTRIFERA. 
15 
gate, subulate, implanted in the fleshy pro- 
boscis. Carnivorous, venomous, marine. 
II. PnoBOSCiDiFEEA. — Head small ; proboscis 
retractile under the base of the tentacles ; 
teeth variable, in three, five, or one longitu- 
dinal series, on an elongated cartilaginous 
tongue membrane. Carnivorous, marine. 
III. Eostrifera. — Head produced into a ros- 
trum, with the tentacles on the side of its 
base ; teeth in seven longitudinal series, on a 
cartilaginous tongue membrane. Phytopha- 
gous, marine, fluviatile, and terrestrial. 
The two first sub-orders are confined to marine 
animals ; the last contains a few fluviatile or terres- 
trial species. 
Sub-order III. Rostrifera. 
Head moderate, with a more or less elongated, 
produced, contractile, transversely-annulated ros- 
trum ; tentacles subulate, far apart, on the sides of 
the base of the rostrum ; eyes on the outer side, or 
behind the base of the tentacles ; teeth on an elon- 
gated linear lingual membrane partially received in 
the visceral cavity, in seven longitudinal series ; the 
central and inner lateral teeth fixed, with a broad 
base ; the two outer lateral teeth versatile, suberect, 
the upper edge lobed. Phytophagous, marine, flu- 
viatile, and terrestrial. 
This group is divided into sections, according 
to the form of the foot, which is modified by the 
