@RDERS. 45 
5. Brancurosrecus, skeleton cartilaginous, 
without ribs; having gill-membranes ; with or 
without gillecovers. 
Examples. Sucker, mullet, sun-fish. 
6. CHoNDROrPTERYGIOUS, skeleton cartilagen- 
ous, without ribs ; gill-membranes wanting ; with 
or without gill-covers. 
Examples. Lamprey, ray, shark, sturgeon. 
V. CLASS ANNELIDA 
IS DIVIDED INTO THREE ORDERS. 
4. Tupsicona, articulated, semi-m: lluseous ani- 
mals, with red blood, encased in calcarevus tubes. 
Examples. Serpula or sea-pipe, amphitrite, 
tooth-shell or dentalium. 
2. Dorsisrancuta, back-gilled Their respira- 
tory organs ure distributed all along the body to- 
wards one side, called the back. 
Examples. Nereis, aphrodite. 
3. Aprancuia, having no gills or other respira- 
tory organs ; but their respiration is performed by 
the entire surface of the skin. 
Examples. Angle-worm, leech or blood-suck- 
er, nais, gordius or hair snake. 
Vil. CLASS CRUSTACEA 
IS DIVIDED INTO FIVE ORDERS. 
4. Decapopta, ten-footed. Head confounded 
with the trunk ; eyes moveable ; mandibles with 
palpi or feelers. 
The gills are situated at the outer base of the 
feet. A numerous order. 
Example. Crabs, lobsters. 
‘= \> 
