OF Ee ae PE RR nee ny Pine eee a Ae aCe Sf ce ee oe a a ere i aie . ite ee ee eee on 
. é 2 " i a a ED an RO aT SSR ee PLN Pe eo oe es " 
based on the principle of Cephalization. 343 
third, including Teliosts, is typical if viewed with reference to 
the Fish-type. Below these, the Dermopters or Myzonts, (in- 
Mammals, Birds, Reptiles. | Fishes. 
Alphatypic, Man. — Selachians. 
Betatypic, Megasthenes. TB acomtientes Chelonians. | Ganoids. _ 
Gammatypic, Microsthenes. Sire ll Lacertoids. | Teliosts, 
H i i oe » 
spent ab t Odtocoids. | Erpetoids. Amphibians.) Dermopters. 
We pass now to Articulates. 
_ 5. Subdivisions of the classes, Insecteans, Crustaceans and Worms 
nto Orders.—(1.) The higher subdivisions in each of the classes, 
, are three in number, none existing 
above the betatypic grade, which is that of Articulates among 
b Articulates. (See 
(2.) Worms are of four types of structure, First, Annelids, 
or typical Worms, including the Branchiates, A ates, ar 
Nematoids—the last the degradational group, and showing this 
In the obsolete body-articulations and some internal characters.— 
Second, Bdelloids, or Molluscoid Worms, including the Hirudines 
; characterized 
or Leeches, Planarians and Trematodes; ¢ by obso- 
