488 



COPEPODA. 



pairs of appendages are both biramous. The second pair of 

 antennae (at 2) is the largest. Its basal portion (protopodite) 

 bears on its inner side a powerful hook-like bristle. The outer 

 ramus is the longest and many-jointed ; the inner ramus has 

 only two joints. The mandibles (md), though smaller than the 

 second pair of antennae, have a nearly identical structure. No 

 blade-like projection is as yet developed on their protopodite. 

 Between the points of insertion of the first pair of antennae is 

 the median eye (oc), which originates by the coalescence of two 

 distinct parts. The mouth is ventral, and placed in the middle 

 line between the second pair of antennae and the mandibles : it 



FIG. 229. SUCCESSIVE STAGES IN THE DEVELOPMENT OF CYCLOPS TENUICORMS. 



(Copied from Bronn ; after Claus.) 



A. B. and C. Nauplius stages. D. Youngest Copepod stage. In this figure maxillae 

 and the two rami of the maxilliped are seen immediately behind the mandible md. 



oc. eye ; at 1 , first pair of antennae ; a/ 8 , second pair of antennre ; md. mandible ; 

 /*. first pair of feet ; / 2 . second pair of feet ; f. third pair of feet ; //. excretory con- 

 cretions in the intestine. 



is provided with an unpaired upper lip. There are two bristles 

 at the hind end of the embryo between which the anus is placed, 

 and in some cases there is at this part a slight indication of the 

 future caudal fork. 



The larva undergoes a number of successive ecdyses, at each 

 of which the body becomes more elongated, and certain other 



