1$. 
20. 
r7- 
19. 
18. 
BH. 
M 
4o. 
Ww O&M S. 
Gordius. Body equal filiform round and fmooth: 
Hirudo. Body truncate at each extremity: head and 
tail dilated when in motion. 
b; Perforated with a lateral Pore. 
Lumbricus: Body round annulate, furnifhed with minute 
concealed prickles. 
Sipunculus. Body round: mouth cylindrical and narrower 
than the head. 
Planaria. Body depretled, with a ventral pore: 
MOLLUSCA. Simple animals furnifhed with limbs. 
A. Muuth placed aliae. 
Aétinia. Body fixed,with a fingle terminal dilatable 
aperture furrounded by tentacula or cirri, 
Clava. Body fixed, with a fingle dilatable vertical 
aperture furrounded with clavate teniacula. 
‘Pedicellaria. — Bedy fixed and furnifhed with a rigid pe- 
duncle. 
Mammaria. Body loofe fmooth, with a fingle aperture 
without cirri. 
Afeidia. Body fixed; with 2 apertures, one of which 
' is terminal,theother placed alittle beneath. 
Salpa. Body loofe; with 2 apertures, one at each 
end. 
Dagyfia. Body loofe angular, open at each end. 
B. Mouth placed befsre. 
Pterotrachea, Body pervious gelatinous, with a moveable 
fin at the head or tail. 
Derris. Body round tapering articulate: feelers 2, 
~€. Mouth placed before: body with a lateral perforation, 
Limax. Feelers 4: vent common with the latera] 
pore. 
Laplyfia. Feelers 4: vent placed above the lower ex- 
tremity. 
Doris. Feelers 2: vent above the lower extremities, 
Tethys. Body with 2 {mall pores on the ieft fide. 
D. Mouth before: body furrounded with feelers on the fore-part. 
41: Holothuria, 
