Pcracarida — Amphipoda. 



45 



shows the parasite in silii in the siiell of the crab. The yellow Table-case 

 mass is the greatly developed brood-pouch, which is distended ^°- "• 

 with eggs. The figure on tlie left represents a younger specimen 

 removed from the crab and further enlarged. The flaps of the 

 empty brood-pouch have been turned back. 



Order 5. — Amphipoda. 



As regards the segmentation of the body, the sessile eyes, and Table-case 

 some other cliaracters, the members of this Order agree with the 



vm 



Fig. 27. 



Gammarus loctista, male, from the side, enlarged, a', antennule ; a", antenna ; 

 ace, accessory (inner) flagellum of antennule ; br, gill-plate ; ex, coxal 

 plate (the expanded first segment of the leg ; gn, the two pairs of " gnatho- 

 pods" (prehensile legs) ; xilp'" , abdominal appendage of third pair ; pr^', 

 prp", first and second peraeopods or walking-legs ; t, telson ; ur, uropod ; 

 II., VIII., second and eighth thoracic somites ; 1, 6, first and sixth 

 abdominalsomites. (From Lankester's " Treatise on Zoology," after Sars.) 



Isopoda, but the body is usually compressed from side to side, the 

 abdominal appendages are not respiratory, and there are gill- 

 plates attached on the inner side of the bases of some of the 

 thoracic limbs. 



The Amphipoda are grouped under three Sub-orders. 



In the Sub-order Gammakidea are included the typical Amphi- 

 poda, in which the body is more or less stout, the abdomen well 

 developed, and the eyes generally small. The most familiar 

 members of this Sub-order are perhaps the Sandhopper, Talitrus 

 saltator, and the Shorehopper, Orckestia (jammarellus. These two 



