TUE COPEPODA 



79 



pletely developed in the Gymnoplea and some Harpacticidae, in 

 which endopodite, cxopodite, and epipodite are distinct, and the 

 protopodite is prochiced internally into a large masticatory lol)e and 

 two smaller distal lobes (Fig. 9, 

 A, p. 13). In the Cyclopidae 

 the epipodite has vanished, the 

 exopodite and endopodite are 

 very small, and only the large 

 masticatory process of the proto- 

 podite persists. In many Har- 

 pacticidae and in the other 

 families the maxillula undergoes 

 various degrees of reduction. 



The two pairs of appendages 

 succeeding the maxillulae are 

 commonly designated the outer 

 (or anterior) and inner (or 

 posterior) maxillipeds, and were 

 for long considered to represent 

 the separated rami of a single 

 pair of appendages. This in- 

 terpretation was put forward 

 by Claus, Avho found that, in 

 the metanauplius stage of 



Fig. 44. 



A, Acontiophorus scutatus, ?, from tU<> siiU^ 

 X 50. Most of the apppmla^vs aie oinitterl. 

 N, suctorial siplioii ; vi, tlie rndinientary sixth 

 ]jair of thoracic Umbs ; l-f-2, the coalesced first 

 Cyclops and other forms, the "'"l second abdominal somites ; 4-1-5, the fourth 

 , I , • r abdominal somite coalesced witli the telson. 



two appeared to arise trom a (After Oiesbrecht.) U, larva of Khitienlanvs 

 eino-lf. nulimpnt H'uwpn linw """"'"s in last metanauplius .stage. The outline 

 Smgie 1 UCUment. tiansen, nO\V ^f the body as seen from above. The lirst three 



ever, has discovered, and the pairs of appenda-es are omitted, but the rudi- 



. ments of the jjostenor apiiendages are seen by 



observation has been COnnrmed transparency through the body. Ku.-", maxillae ; 



1 n • ^ \ J. 11. rii mxp, maxilliiieds, separateil from the maxillae 



by Giesl)recht and by OlaUS by the line delining the first thoracic somite ; 



himself, that in the larvae oi ■^^xfterGie>,MZr'''^ ^''''''^ ^ 

 certain marine GymnojDlea 



(Eucalanns, Bhinadanus, Pontella, etc.) in which the body is more 

 elongated than usual, the rudiments of the two appendages are not 

 only (juite distinct, but are separated from each other by the suture 

 line which marks ott" from the head the so-called first thoracic 

 somite (Fig. 44, B). The " outer (or anterior) maxillipeds " are 

 therefore the maxillae, while the inner (or posterior) pair, for which 

 the name maxillipeds may be retained, must be regarded as the 

 first of the thoracic series, and the somite corresponding to them 

 is, at least in some cases, coalesced with that which bear.s the first 

 pair of swimming-feet. The maxilla in its most fully developed 

 form consists of a flattened and shortened axis of, at most, eight 

 segments, of which the first and second each bear two, and the 

 third a single endite (Fig. 41, C). In the Gymnoplea this appendage 

 is beset Avith plumose setae, which act as a net in collecting food- 



