PA UAS1TIC COPEPODS—CALIGID.E— WILSON. 



503 



edge is crenated and fringed with long cilia (fig. 6, a). This flap is 

 flexible and capable of more motion than the remainder of the lip, but 

 to call the latter "immovable' 1 (Pickering and Dana) is certainly mis- 

 leading. The whole mouth tube moves together and freely, and cer- 

 tainly the dorsal portion of it is as movable as the ventral. In Oaligus 

 rapax the anterior portion of the chitinous margin, instead of being- 

 concave, is convex like the lower lip, and projecting in front of it is 

 a narrow flexible membrane flap, with its front edge incised at the cen- 

 ter and fringed throughout with cilia (tig. 10). 



The statement of Pickering and Dana that the mouth "appears to 

 be composed of the upper and lower lips, united with the different 

 parts of a pair of maxilla; " (1838, 

 p. 73) can not stand. Those au- 

 thors made no attempt at any 

 explanation of the position or 

 connection of the maxilla? re- 

 ferred to, except to state that 

 they corresponded to the first 

 pair of maxillae in decapod Crusta- 

 cea. And even this was not stated 

 directly, but in a roundabout fash- 

 ion, for they found a single pair 

 of appendages which they said 

 corresponded to the second max- 

 illa? in decapod Crustacea, but 

 which they called the first maxil- 

 lipeds. They proved to be in 

 realit}' the second antenna?; it 

 must have been, therefore, the 

 first maxillae which they thought 

 were combined with the upper 

 and lower lips. But we have al- 

 ready seen that both pairs of 

 maxillae arc fully accounted for 

 outside the buccal tube. And A. Scott has shown by the innervation 

 in Lepeophtheincs pectoralis that the claws which Pickering and Dana 

 considered as appendages of their "first maxillipeds " are really the 

 first maxillae. 



Of the two pairs of maxillipeds, the first are situated about halfway 

 bet ween the ;i|>c\ of tin' mouth and tin' lateral margin of the carapace. 

 Bach one of this paii' is two-jointed, tin 1 basal joint moderately stout 

 while the longer terminal joint is very slender and terminates in two 

 or three short and stout spines. Their function is probably that of 

 keeping the mouth clean of foreign matter by a sort of combing 

 mot ion (fig. 1 1 ). 



The second maxillipeds arise near the mid line, a little posterior to 



Via. 10.— Dorsal surface op the mouth tube 

 op Caligus rapax in an advanced chalimus 

 stage, r', rod on lateral margin of frame- 

 work of upper lip. 



