CLASSIFICATION. v ;1 



These sometimes resemble worms found in the other 



classes or orders, while differing from them as to their 



locality. They have been arranged into the following 



sub-orders : 



(1). Nematoidea or Nematoids, Round Worms, Thread Worms, 



Pin Worms, Guinea Worms. 



(2). Acanthocephala, (Spine-headed,) Hooked Worms. 

 (3). Trematoda, (from Gr. trema, hole, having Sucker-like 



openings,) Fluke Worms, &c. 

 (4). Cestoidea, (Gr. Kestos, girdle,) Tape Worms. 

 (5). Cystica, (Gr. Kustis, a bladder,) Hytatids or Bladder- 

 like Worms. 



MOLLUSKS. Two GRAND DIVISIONS: 



CepHALATA (with heads) or UNIVALVES. 

 ACEPHALA (without heads) or BIVALVES. 

 I. CEPHALATA : Three classes or Sub-divisions, viz. 



(1). (tauiOPO*, suihhead. Two section,. 



Dibranchiata, (Two branchiae,) Cuttle-fish. 

 Tetrabranchiata, (Four branchia?,) Nautilus, Ammonites, &c. 



i Wing-footed, i. e., ) 

 wing-like arms &amp;gt; Three families, 

 for swimming. j 

 HyalaidcE, Hyalaea, Cleodora. 

 Limacinida, Limacina, Spiralis. 

 Clionidce, Clio. 



(3). G.ST.BOPOOS, 



(1). Pulmobranchia (Lung-like Gills). (Four families.) 



Limacidee, (from Limax,} Slugs. 



HelicidcB, (from Helix,) Snails. 



Auriculidce, (from Auricula,} Ear-shaped Shells. 



Limntzidce, ( &quot; Limncca, Aquatic-Snails. 

 (2). Pectinibranchia, (Comb-like gills.) (Nine families.) 



Trochida, (from Trockus,) Trochi. 



Turbinidce, (from Turbo,} Turbines, Periwinkles. 



Muricidce, ( &quot; Murex,) Murices. 



Strombidce, ( &quot; Strombus,) Conch-Shells. 



Buccinidce, ( &quot; Buccinum,} Harp-Shells, Whelkfl. 



Cyprceida, ( &quot; Cyprcea,} Cowries. 



Conidce, (from Conus,) Cones. 



Volutidce, (from Valuta,) Volutes, Olives, Mitres. 



Capuloidea, (from Capula,) Cup-shaped Shells. 



Tubulibranchia, (Tubular-gills,) Vermetus, Siliquaria. 

 Scutibranchia or j Gills shielded, by ) Tr n i: nf : a 

 Aspidobranchia, \ the Shell. 



f Gills circular, i. e., 

 Cyclobranchia, &amp;lt; around the body of 



( the animal. 



