THE COPEPODA. 



235 



amined, appears single, shines through the carapace, and at 

 the sides of the latter, two coiled tubes with clear contents, 

 the so-called shell-glands, are seen. 



Four distinct and movable somites succeed the carapace, 

 and gradually diminish in diameter. The body then suddenly 

 enlarges, and becomes divided, in the female, into four seg- 

 ments, the last of which gives attachment to two long setose 

 styles, which possibly represent another somite. There is a 

 well-developed and prominent labrum (or conjoined epistoma 

 and labrum) in front of the mouth, and behind it is a bilobed 

 metastoma. The first pair of appendages are the long and 



Fig. 60.— Cyclops.— Side-view of an adult female carrying a pair of ovisacs, and ven- 

 tral view of the head, showing the labrum, metastoma and appendages of the left 

 side. 1', eye ; II', antennule ; III', antenna; IV, mandible; V, first maxilla; 

 VI', second maxilla (erroneously marked VII') ; a, outer ; b, inner division ; 1, 2, 

 3, 4, 5, thoracic limbs ; R, rostrum ; lb, labrum ; mt, metastoma. 



many-jointed antennules, which are the chief organs of loco- 

 motion. These are succeeded by the short and few-jointed 

 antennae. The third pair of appendages, or first pair of gna- 

 thites, differ from the corresponding limb in Limulus in the re- 

 duction of the greater part of the appendage to a rudiment 

 terminated by setae, while the strong basal part is the princi- 

 pal gnathite or mandible. The second pair of gnathites are 

 strong and incurved ; following upon these is a third pair of 



