the inner surface with very thin cuticle. They bear a 

 few scattered spines on their edges, which overlap, the 

 anterior edge of one plate lying over the posterior edge of 

 the one in front. On the inner side of the base of each of 

 these legs is borne a soft, thin, flexible branchia, oval in 

 form and covered by extremely thin cuticle ; it is marked 

 by distinct transverse bands of tissue (PL lY., fig. 1 hr., 

 and fig. 3). In the female a pair of thin lamellae, edged 

 with long hairs, are also borne on each segment, internal 

 to the brauchise. These fold over in the middle line to 

 form the brood pouch containing the developing ova. 

 They are the oostegites, and are absent in the young 

 animal. The first four thoracic segments increase in 

 size from before backwards. The terga are produced at 

 their lower edges into short, crescentic epimeral plates 

 (PI. II., epim. p.). They only slightly overlap one 

 another, the posterior edge of each tergum lyiug above the 

 anterior edge of the succeeding one, except in the case of 

 the first segment, in which the anterior edge of the tergum 

 overlaps the cephalic shield, so as to allow the head to be 

 bent down with ease. The last three segments of the 

 thorax bear long perseopods, directed backwards, with 

 enlarged basal joints ; these are more slender and 

 elongated in G. pulex than in G. locusta (PL II., 7-?e/-. 3, 

 4, 5). These segments gradually decrease in size from 

 before backwards, and their terga, which are produced 

 into short, broad epimeral plates, overlap to a large extent, 

 so as to allow considerable flexion of the body. As in 

 the other free thoracic segments, their appendages bear 

 branchise. In the female, the oviducts open at the base 

 of the fifth pair of legs ; in the male, the vasa deferentia 

 open at the base of the seventh pair of legs on the summits 

 of a pair of small tubercles. 



The abdomen consists of six segments and the telson 



