ARTHROPODA 



283 



multiarticulate flagella ; the second antenna has a large squama 

 or scale. 



The mandibles hear a palp, and the two pairs of maxillae 

 are small and weak. The maxillipedes are the most charac- 



Fig. 164. — Squilla mantis, seen from the left side. After Leuckart and Nitsche. 



1. 1st antenna. 8-10. 1st to 3rd biramous swlmming- 



2. 2nd antenna. lees. 

 2'. Scale, exopodite, of 2nd antenna. 



3. 1st maxillipede. 



4. 2nd maxillipede. 



5. 3rd maxillipede. 



6. 4th maxillipede. 



7. 5th maxillipede. 



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 f9r 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 



