BRITISH ASSOCIATION. 273" 



is common to find Ligia with them in a rudimentary state. They 

 preserve their comparative characters, even in the young state of the 

 animals, the only difference being, that the accessory lobe is somewhat 

 more strongly marked, and afford the most valuable of all the characters 

 which I have mentioned, for fixity of a type. 

 The order of value of these characters is : — 

 Generic. 1st. Appendages of, and last ring of abdomen. 



2nd. Arrangement and form of external antennae. 

 3rd. Proportional development of coxae of abdominal rings. 

 4th. Development of antennal rings. 

 Familiar. 1st. Appendages of last ring of abdomen. 

 2nd. Proportional development of coxae. 

 3rd. Arrangement and form of external antennae. 

 The characters of the internal antennae and of the parts of the mas- 

 ticatory apparatus are chiefly of familiar import : they are so difficult to 

 establish that I have omitted them in this rough sketch, which is put 

 forward merely as an attempt at a more natural arrangement of these 

 genera than those published. It will be found that I have also omitted 

 all mention of the internal anatomy for the present. 



Many of the foreign genera are so scantily described, that it would 

 be foolish to attempt anything like generalities here, and this whole 

 paper, as I said before, is merely provisional, the rather as I hope 

 before long to examine into, not merely genera, but species, as at pre- 

 sent far too many false ones incumber our systems. 



Provisional Arrangement of Families, 

 The genera described are British. 



Family.— TYUDM. 

 Genus 1. — Tylos (Latreille). 



Family.— AEMADILLID^]. 



Genus 1. — Armadillo (Brandt), 

 Genus 2. — Cubaris (Brandt). 

 Genus 3. — Sph.zerillo (Dana). 



Genus 4. — Armadillium (Brandt). 



Body semi-globose ; head rounded, median lobe minute, arcuated, as 

 a triangular shield. External antennae : second joint of peduncle lobed. 

 Tige three-jointed, hairy, rounded. Coxae of first and sixth abdominal 

 rings obsolete. False feet of last pair : peduncle flattened, lamellar, 

 truncate. Ischium flattened, truncate; external angle produced. Ac- 

 cessory lobes arising from base. Accessory filament flattened, club- 

 shaped, concealed. 



