44 REVIEWS AND BOOK NOTICES. 
the bivalve phyllopods (Estheria) of our fresh-water pools are 
daily mistaken by collectors for species of Cyclas. On the other 
Lingula pyramidata. 
hand certain worms, such as the flat worms or Planarians, have ) 
been regarded as allied to the snails and slugs by good naturalists. 
We will now attempt, so far as is possible, to condense the 
paper of Professor Morse by giving his chief arguments for con- 
Fig. 2. ; Fig. 3. a i 
l b ; 
Tra of Lingula. 
b, bands suspending intestine in perivis Transverse section of Annelid, after 
ceral cavity; i, intestine; s, segmental b, bands suspending intestine in per 
- organ; 0, ovaries; 1, liver; g, gills; se, se, ral riggs i, intestine; s, segmental 
sete. se, se, sete 
Fig. 4. Fig. 5. 
Molluscan archetype, after Carus. 
Transverse section ot monia- 
Can archetype, after Caru 
idering the “‘Lamp-shells” as worms. He first defines the t 
classes. The worms haye an elongate form, while that of 
è 
