4-78 HISTORY OF ENTOMOLOGY. 
I have before sufficiently noticed these Classes, or 
Orders as Mr. MacLeay terms them, of the Sub-king- 
dom Annulosa : I shall here therefore only throw out 
a few remarks on their composition. With regard to 
their circular distribution in the Crustacea, Mr. MacLeay 
thinks the series runs from the Branchiopods or Mono- 
culus L. to the Decapods or Cancer L. ; and so on, till by 
means perhaps of the genus Bopyrus, which Fabricius re- 
gards as a MonoculuSi it returns to the Branchiopods 
again. This circle, through Porcellio, a kind of wood- 
louse, &c, which has only a pair of antenna? and at first 
but six legs, is connected with the Ametabola Class, 
which beginning with Glomeris goes by the other Chilo- 
gnatha [lulus L.), having also six legs at first, and certain 
Vermes to the Auoplura, and terminates in the Chilopoda 
(Scolopendra L.) their cognate tribe 3 . From the Ameta- 
bola Mr. MacLeay proceeds to the Ma?idibulata, between 
which two groups he has discovered no osculant one, but 
he takes the Anoplura of the former as the transit to the 
Colcoptera in the latter ; from whence passing to the Or- 
thoptera, &<;., he finally returns by the Hymenoptera. 
Between the Mandibidata likewise and Haustellata he 
finds no osculant class : but as the affinity between the 
Trichoptera and Lepidoptera is evident, proceeding by 
the Homoptera he returns to the Lepidoptera by certain 
Diptera, as Psychoda, &c. From the Aptera Lam. or 
Pulex L. he passes by the osculant class Nycteribida to 
the Arachnida ; and beginning with the Acaridea, he 
goes to the Scorpionidea, and so to the Aranidea or spi- 
ders, which he connects with the Decapod Crustacea ; — 
* See Vol. III. p. 25—. and above, p. 31)4 — . 
