which an appendage of the second pair of maxillae (f) plays. On four
feet (i, k, l, m) are the rudiments of the lamellae which subsequently
form the brood-cavity.)

The similar number of segments* occurring in the Crabs and Macrura,
Amphipoda and Isopoda, in which the last seven segments are always
different from the preceding ones in the appendages with which they are
furnished, could only be regarded as an inheritance from the same
ancestors.

(* Like Claus I do not regard the eyes of the Crustacea as limbs, and
therefore admit no ocular segment; on the other hand I count in the
median piece of the tail, to which the character of a segment is often
denied. In opposition to its interpretation as a segment of the body,
only the want of limbs can be cited; in its favour we have the relation
of the intestine, which usually opens in this piece, and sometimes even
traverses its whole length, as in Microdeutopus and some other
Amphipoda. In Microdeutopus, as Spence Bate has already pointed out, one
is even led to regard small processes of this tubular caudal piece as
rudimentary members. Bell also ('British Stalk-eyed Crustacea' page 20),
states that he observed limbs of the last segment in Palaemon serratus
in the form of small moveable points.

The attempt has often been made to divide the body of the higher
Crustacea into small sections composed of equal numbers of segments,
these sections consisting of 3, 5 or 7 segments. None of these attempts
has ever met with general acceptance; my own investigations lead me to a
conception which nearly approaches Van Beneden's. I assume four sections
of 5 segments each--the primitive body, the fore-body, the hind-body,
and the middle-body. The primitive body includes the segments which the