344 Dana on the Classification of Animals 
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Aiashuhent. and in an. 1 up- -and-down movement of the too in 
loc ocomotion, Mollusk-like, instead of the worm-like lateral move- 
ment of the Annelids. The fact of this mode of movement has 
been recently made known to the writer by Dr. Wm. C. Minor, 
as a distinctive feature of the Bdelloids. Quatrefages remarks 
‘that the Planarians and Trematodes may well be regarded de- 
graded forms of the Hirudines, and the three tribes are arranged 
in one group by Burmeister. —Third, Gephyreans (of de Quatre- 
fages), or Sateen 2 orgesieiar es Worms, including the gen- 
era, Echiurus, Sipuncula, ete.’—Fourth rg, or Protozoic 
Worms, ‘atbeling the Cestoids, in which there is no normal 
digestive system, and the segments are ‘eda penal self- 
nutrient.° 
- The orders of these classes of Articulates are the following: 
Insecteans. Crustaceans. Worms. 
Alphatypic, 
Betatypi Insects. Decapods. Annelids. 
Gammatypic, Spiders. Tetradecapods. | Bdelloids. 
ys Cay tage Myriapods. | Entomostracans. | Gephyreans. 
& meee Cestideans. 
6. Subdivisions of the orders of Insecteans and Crustaceans into 
tribes.—(1.) The orders of Jnsecteans have each three divisions, 
exceptin ‘that of Myriapods in which but two have been reco 
nize he three of Insects are indicated on pages 328, 385. 
The fact that Insects are, in type-idea, flying Articulates gives 
special unborn to the wings in claceifonean The first order 
includes the Prosthenics, in which the anterior wings are flying 
wings, as the Hy menopters, bas: Neuropters, Lepidopters 
and Homopters. The second consists of the Metasthenics or 
Elytropters, in which the anterior wings are not used in flying, 
or but little so, as the Coleopters, Strepsipters, Orthopters and 
Hemipters. The Hemipters and Homopters, united in one aie 
by most entomologists, are hence profoundly distinct. The th 
tribe, or Apters, embraces the Lepismids and Podurellids; the 
remaining Apterous insects being distributed eee the other 
7 7 The me urioid characteristics are well exhibited by de ag vatrefages in Part 
pt aa ath pnd cyend, of Recherches Anatomi et Zool. onivers fe aites pendant un 
tes de la Sicile, ete, in 3 ee veri de Quatre- 
a or and g van Beneden an 
