494 



CRUSTACEA MALACOSTRACA. 



joint. The maxillipeds * (first thoracic appendages) are in many 

 cases seven-jointed (as are the succeeding appendages), but their 

 basal segments are fused in the middle line, forming an under- 



pin. 305. MX' first maxilla ; mx" second maxilla ; J/j-/ maxilliped of Gam.ma.rus (from 

 Claus) ; En endopodite ; L basal endite. 



lip, comparable with the labium of insects. The two succeeding 

 segments of the maxillipeds bear lobes on their inner margins 

 which project forward on the median side of the 4-jointed ter- 

 minal part of the appendage which forms the 

 palp. They are without an epipodial plate. 

 In the Hyperina the maxillipeds are repre- 

 sented by a median plate (Fig. 306), bearing 

 a pair of small setose lobes in front. 



In the Laemodipoda the segment which in 

 other Amphipods is the first free thoracic seg- 

 ment is fused with the head to form a cephalo- 

 thorax. 



The legs of the seven free thoracic segments 

 are disposed in two groups, the four anterior 

 having the terminal segments directed backwards and the three 

 posterior having those segments directed forwards. 



The basal segments (coxopodites) of the thoracic legs are in 



* The following nomenclature is adopted by Stebbing, in his monograph 

 on the Gammaridae (the Gammarina of this work) in Das Tierreich. 

 Thoracic appendage 1 = maxilliped 



appendages 2 and 3 = gnathopods 1 and 2 



,, 4 to 8 = peraeopods 1 to 5 



Abdominal ,, 1 to 3 = pleopods 1 to 3 



,, 4 to 6 = uropods 1 to 3 



Fin. 306. Hyperia gal- 

 ba. The maxillipeds 



(after Gerstaecker). 



