ARTHROPODA 28 
Oo 
multiarticulate flagella ; the second antenna has a large squama 
or scale. 
The mandibles bear a palp, and the two pairs of maxillae 
are small and weak. The maxillipedes are the most charac- 
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Fic. 164.—Squilla mantis, seen from the left side. After Leuckart and Nitsche. 
1. 1st antenna. 8-10. Ist to 3rd biramous swimming- 
2. 2nd antenna. legs. 
21. Scale, exopodite, of 2nd antenna. 11-16. Ist to 6th abdominal _ legs, 
3. 1st maxillipede. the anterior five pairs bearing 
4, 2nd maxillipede. branchiae. 
5, 3rd maxillipede. 17. Branchiae. 
6. 4th maxillipede. 18. Penis. 
7. 5th maxillipede. 19. Eyes. 
teristic appendages of this order; there are five pairs of them, 
turned forward towards the mouth (Fig. 164). The anterior 
pair are thin and feeble, but terminate in a small pair of sub- 
chelae which help to hold the prey; the second pair are the 
largest appendages of the body. Their terminal joints are 
strong and toothed, and shut down upon the penultimate like 
the blade of a knife into its handle; this arrangement has been 
termed subchelate, and it exists in all the maxillipedes of this 
group. The three succeeding maxillipedes are smaller, and 
terminate in small rounded subchelate joints. The three free 
thoracic segments carry biramous swimming-feet. The six 
abdominal segments also bear each a pair of swimming-feet, 
which are remarkable for carrying the gills on the external 
ramus. ‘The first pair are modified in the male in connection 
with reproduction. 
The elongated condition of the heart, which stretches from 
the thorax through the abdomen, is doubtless correlated with 
