THE COPEPODA 



79 



pletely developed in the Gymnoplea and some Harpacticidae, in 

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

 protopodite is produced internally into a large masticatory lobe 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 fto ' 44 ' 



, V i r J i* 4 A Acontwphorus Kutatus, 9, from the side, 



by ClaUS, Who found that, in x 50 . Most of the appendages are omitted. 



rnnaiinliiT? <jfra<rp nf *, suctorial siphon ; vi, the rudimentary sixth 



t a n a U p 1 ] r pair of thoracic limbs ; 1 +2, the coalesced first 



and Other forms, the and second abdominal somites ; 4+5, the fourth 



- abdominal somite coalesced with the telson. 



tWO appeared tO arise irom a (After Giesbrecht.) B, larva of Rhinmlanus 



single rudiment. Hansen, how- 

 ever, has discovered, and the 



observation has been Confirmed transparency through the body, mz", maxillae ; 

 i_ n i. \. J v m ""P' maxillipeds, separated from the maxillae 



by Uriesbrecnt ana by UlaUS by the line defining the first thoracic somite ; 



himself, that in the larvae of fa r Sb^cht) 00 ' 1 prir * f 8Wimming - feet - 

 certain marine Gymnoplea 



(Eucalanus, Bhincalanus, Pontella, etc.) in which the body is more 

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

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

 line which marks off 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 bears 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 with plumose setae, which act as a net in collecting food- 



