236 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



protopodite, which carries a jointed exopodite (ex) and 

 endopodite (en). All the joints carry movable setae, 

 and the terminal joints also bear long plumose hairs. 



3. The third pair of appendages (M) are much like 

 the second, and become the mandibles of the adult. 



c. The dorsal surface is almost entirely covered by the 

 oval carapace, near the anterior margin of which is the 

 black double eye-speck (o). 



d. Posterior to the carapace is the last abdominal seg- 

 ment, which carries the anus («), and a pair of terminal 

 setae. 



Fig. 128. 



Fig. 128. — Young Cyclops, with two pairs of fully-developed thoracic 

 limbs, and a rudimentary third pair. (From Claus, in Bronn's Klassen 

 u. Ordnungen des Thierreichs. Arthropoda Taf. xiii., Fig. 6.) 



a. Abdomen, c. Carapace, d. First antenna, e. Second antenna. 

 /. Mandible, g. First maxilla. /;. Second maxilla, i. First thoracic 

 appendage, j. Second thoracic appendage, k. Rudimentary third tho- 

 racic appendage, t. Thoracic somites, o. Ocellus. 



e. The digestive tract consists of : — 



(i.) A short oesophagus, which runs upward and for- 

 ward from the lower surface of the labrum. 



(ii.) The dark-colored stomach (s). 



(iii.) The pear-shaped thick-walled intestine. 



/. Ui)on each side of the stomach is a transparent cir- 

 cular tube, the shell-gland, which does not seem to be 

 furnished with an external opening. 



i 



