APPENDAGES OF THE PENZIDEA 275 
two- or three-jointed eye-stalks, flagella of the first 
antennee not longer than the carapace, a two-jointed man- 
dibular ‘palp,’ the third maxillipeds long and _ pediform, 
the first three pairs of trunk-legs carrying exopods, the 
fourth and fifth pairs 
not longer than the 
preceding, the pleo- 
pods with two foliace- 
ous branches in every 
pair except the first, 
which in the male has 
a large membranous 
appendage attached to 
the base. This ap- 
pendage, called by 
Spence Bate the pe- 
tasma or curtain, is 
rudimentary in the 
female. In this genus 
there are no podo- 
branchie. ‘The first 
Species assigned to it 
by Fabricius was the 
large Penceus monidon, 
which occurs in the Fic. 20.—Sergestes Atlanticus (Milne-Edwards), first 
neighbourhood of Cey- eee ea ae piles > Deteeui Saeco 
lon, Western Australia, 
and the Philippines, and is perhaps identical with the 
Japanese Penceus semisulcatus of de Haan. Penceus cara- 
mote (Risso) is found in the Mediterranean and Atlantic, 
and is sometimes taken in English waters. 
Penceus canaliculatus, Olivier, appears to extend with 
little variation from Japan to Australia, and to differ only 
in small particulars from Peneeus caramote. ‘Thus, it has 
nine teeth instead of twelve on the dorsal crest, straight 
instead of wavy ridges on either side of the carina of the 
carapace, the spine on the outer margin of the first joint 
of the first antenne not nearly instead of quite reaching 
the extremity of the eye, no tooth on the second joint of 
