ARCTURUS LONGICORNIS. 367 
The first three segments of the pereion are very short, 
with a produced lateral margin (representing the coxa, 
or first joint of the legs, and) concealing the base of the 
legs, the first pair of which are alike in form, but shorter 
than the others, and evidently perform the office of an 
extra pair of foot-jaws; indeed, from the manner in which 
this, as well as the three following pairs of feet, are carried 
over the mouth, it is probable that they are all employed 
rather as such than as locomotive organs. The very slender 
structure of these three pairs of legs, which are all formed 
alike and are strongly ciliated within, is also confirmatory 
of this opinion. The first pair of legs are also ciliated, 
the cilie arising in double rows, and being often bearded, 
as is also the case with the three following pairs, in 
which, however, only two of the hairs situated near the 
extremity of the penultimate joint are thus bearded. 
The fourth segment of the body is very long, occupy- 
ing more than one-third of the whole length of the 
animal, and being perfectly cylindrical in the males, in 
which sex it is without any orifice or inferior lamelle, 
and is the narrowest part of the body; but in the female 
it is as wide as the head, and furnished beneath with two 
thin membranous plates, lapping over each other, and 
serving as an envelope for the eggs, which are of a red 
colour and kidney-shaped. The fourth pair of legs are 
attached below the anterior angles of thissegment. The 
three succeeding segments are short, rounded at the sides, 
and respectively furnished with a pair of strong short 
legs, well formed for prehension, having the last joint 
terminated by a bifid hook. These legs are not ciliated, 
and have a backward direction. 
The tail, seen laterally, appears to consist of only two 
segments, of which the first is almost globose, and. the 
second oval, terminating in a strong spine; seen from 
