The antennules (A,) in harpacticoids are short (4-10 

 segments) and usually bear 1 or 2 aesthetascs 

 (transparent, setalike organs) somewhere on the append- 

 age (Fig. 3). The male A.'s'are usually swollen and 

 hooklike and are used as grasping appendages (Fig. 4). 



The antennae (Aj) are biramous and each consists of a 

 basis, an endopod, and a small (1- to 6-segmented) ex- 

 opod (Fig. 5). Two terms necessary for understanding the 

 structure of the Aj must be introduced since they appear 

 in the key which follows, i.e., basis and allobasis. An A2 



with an allnhasis is one in which the exopod originates on 

 the first endopod segment (Figs. 5 and 70). An A, with a 

 basis is one in which the exopod originates from the 

 basis, and not the first endopod segment (Fig. 69). An 

 allobasis Ai often appears as having but 2 segments, 

 whereas the basis A; appears as 3-segmented. 



The mandibles, maxiUulae, maxillae, and maxillipeds 

 are complex and specialized feeding structures which, 

 although furnishing extremely useful specific characters, 

 necessitate descriptions and explanations beyond the 



Figures 3-6. — Enlargment of flome harpacticoid body parts: 3) female antennule (A,); 4) male antennule 

 (A.), note modification an f^raspine organ; ^) generalized antenna (A^); 6) generalized harpacticoid leg 

 with partK labeled. The leg figured has a 3-8egmented exopod and a 3-segmented endopod, but either ramus 

 may have I, 2, or 3 segments, depending on the species. 



