APPENDAGES AND NERVOUS SYSTEM OF APUS CANCRIFORMIS, 361 
EXPLANATION oF Wooncut, Fie. 1. 
In all the figures the endites are numbered from the basal one forward, 
as 1, 2, 3, 4, 5, 6. The proximal endites are often rudimentary 
or connate. In J/ and J//J endite 5 is suppressed, as becomes 
obvious on comparison with JV. is the flabellum of the Apus limb, 
or its equivalent. (epipodite); p, the sub-apical lobe; B, the bract ; 
B', a second bract in XVJZ; 5, the fifth endite or exdopodite ; 6, the 
sixth endite or ezopodite. 
I. First maxillipede of Carcinus menas (after Boas, in ‘Studier over 
Decapodernes Slegtskabsforhold,’ Kopenhagen, 1880). 
Il, Ditto of Pagurus tuberculatus (after Boas). 
IIT, Ditto of Callianassa (after Boas). 
IV. Ditto of Caridina (after Boas). 
V. Second maxilla of Astacus fluviatitis. 
VI. First maxillipede of ditto. 
VII, Third maxillipede of ditto. 1, 2, rudimentary endites of the coxo- 
podite; 3, 4, of the basipodite; 5, the ischiopodite or basal segment of 
the polyarthrous endopodite. 
VIII. Second maxilla of Sergestes (after Claus). 
IX. First maxillipede of ditto (after Claus). 
X. Third abdominal foot of Palinurus (female), after Boas. 
XT, Second maxilla of Zoea of Palemonetes (after Boas). 
X/T, The same at the Mysis stage. 
XII. First maxillipede of same at the Mysis stage (compare with XY VT). 
XIV. Abdominal foot of Nebalia (after Claus), compare with I// and 
with X. 
XV. First rudiment of thoracic foot of Branchipus (after Claus). 
XVI. Thoracic foot of larval Apus (after Claus). 
XVII. Thoracic foot of Branchipus Josephine, after Grube. 
XVIII. Second proral appendage (second Nauplius’ limb) of larval 
Apus. 
PYLY. Second thoracic foot of male Limnetis (after Grube). 
Comparison of the appendages of Apus cancriformis with 
those of other Phyllopoda and of the Nauplius larva.—The 
appendages of the other species of Apus which have been 
described differ from those of A. cancriformis as to the 
number present in the post-genital or abdominal region. 
The length and the number of the joints in the filamentous 
endites of the first thoracic feet appear also to afford 
distinctive specific characters. 
In other Phyllopoda the truncal appendages conform very 
closely to the plan of structure exhibited in Apus, presenting 
a corm with six endites, often a subapical lobe, and two 
exites. Branchipus Josephine of Grube (woodcut, fig. 1, 
XVII) is remarkable for possessing a third exite. 
In the genera Branchipus, Artemia, Limnetis, Limnadia, 
and Estheria, the truneal appendages present special modi- 
fications of the constituent parts not shown in any part of 
the series in Apus, although the corresponding ‘apophyses’ 
are readily identified. One of the most remarkable modi- 
VOL, XXI.—NEW SER. AA 
