MORPHOLOGY OF BATHYNELLA AND ALLIED CRUSTACEA. 495 
Apseude s, where, according to Claus, the rami are coalesced 
at the base so as to form an apparent fourth segment of the 
peduncle. In the Phyllocarida the peduncle consists of four 
segments. 
At first sight, the antennule of Bathynella (Text-fig. 6) 
seems to bear out Chappuis* description. On the proximal 
side of the vestigial inner ramus it presents three large 
segments following upon two extremely short basal segments, 
the latter together representing the first segment as figured 
by Vejdovsky. A careful examination of these short seg- 
Text-fig. 6. 
Bathynella natans, $. Antennule of left side, dorsal view. 
Drawn from a cleared specimen in which some of the finer 
setae are missing, i. r. Vestige of inner ramus. 
ments, however, leaves some doubt as to their being real 
segments of the peduncle (Text-figs. 2, 3, and 6). The 
proximal of the two forms a ring of chitin, not defined from 
the exoskeleton of the head by any articulation or line of 
suture, although it is overlapped above by a slight fold 
forming the frontal margin of the cephalic tergite. It may 
well be that this apparent proximal segment is simply the 
everted margin of the socket with which the antennule 
articulates. The second segment has a less firm outline than 
the first and the succeeding segments; its surface (in the 
single specimen in which I examined it closely) was irregu- 
larly folded and wrinkled, and it may be nothing more than 
the articular membrane of a joint that has more than the 
usual range of motion. At all events there appears to be no 
