THE ONISCID Ai 427 
simplicity of this arrangement is rather rudely disturbed, 
when it appears that Porcellio has to be divided into seven 
genera or sub-genera and Oniscus into five, and in fact with 
one or two recent additions the Oniscidze contain twenty- 
one genera instead of only six. Little more can he done 
here than to mention their names. 
Poreellio, Latreille, 1804. In this genus, after restric- 
tion, Budde-Lund describes seventy-one species, besides 
giving the names of more than a score recorded without 
description or imperfectly described. To this long list 
additions have since been made, as lamellatus, Uljanin, 
from the Mediterranean and the Azores; cristatus, Dollfus, 
from Surinam; Marion, Aubert and Dollfus,from Marseilles ; 
provincialis, Aubert and Dollfus, from Salon, in one of the 
districts of Provence, the most arid and remote from human 
habitations. Moreover, four or five new species from Syria, 
chiefly collected by Dr. Th. Barrois, have been named by 
M. Dollfus during the year 1892. Only the following 
four species out of this extensive genus have been re- 
corded in Great Britain. 1.—Porcellio scaber, Latreille, is 
extremely common over the whole of northern and central 
Europe and the North of America. It extends to Green- 
land, and none of the land Isopoda range further to the 
north than this does. It is said also to reach the Cape of 
Good Hope and to have been found in Central America. 
2.—Porcellio pictus, Brandt, is perhaps the same as the 
earlier Porcellio spinicornis, Say. It is distinguished by a 
large apical tooth on the second jointof the second antenne, 
and by the black and yellow markings of the perzon. 
Together with the preceding species it belongs to a section 
of the genus in which the last segment is triangularly pro- 
duced, with a sharp apex. 3.—-Porcellio dilatatus, Brandt, 
belongs to a section in which the last segment is produced 
with a rounded apex. It does not appear to be at all 
common in Great Britain. 4.—Porcellio levis, Latreille, 
belongs to a group distinguished from that which includes 
all the other three by having the hind margins of the first 
three pereeon-segments less laterally sinuate, the side- 
plates less, with the hinder angles in the earlier segments 
