NO. 1573. 



PARAStriC COPEPODS— WILSON. 



329 



supplementary means of differentiation. In the genus Pandarus, 

 which may be taken as the type of the subfamily, there are four pairs 

 of these pads (fig. 2). 



The first pair are connected with the bases of the first antemia?, 

 are elliptical or oval in outline, and stand close to the lateral margins 

 of the carapace, sometimes even projecting beyond the margin. 

 The second pair are connected similarly with the bases of the second 

 antennge, are usually circular or oval in outline, and stand inside of 

 and posterior to the first pair. The long diameters of both pairs 

 are parallel with the body axis, as a rule. The third pair are con- 

 nected with the bases of the second maxillipeds, are sometimes cir- 

 cular and sometimes elliptical in outline, 

 and stand on either side of and close to the 

 mid line about in the center of the ventral 

 surface of the carapace. The fourth pair 

 arise as prominences on the bases of the 

 first pair of dorsal plates in the female, or 

 the lateral processes of the first free seg- 

 ment in the male. The exterior margin of 

 each of these plates reaches forward under 

 the carapace to a point opposite the bases 

 of the first legs, and here at its antero-lateral 

 corner the pad is developed. These pads 

 are elongate-elliptical in outline, their long- 

 diameters parallel with or slightly inclined 

 to the body axis. There are also in some 

 genera pads on the basal joints of the 

 swimming legs; these are usually elliptical, 

 with their long diameters at right angles 

 to the body axis (fig. 3). 



The first two pairs of pads are the most 

 important, and the necks or stems by which 

 they are united to the ventral surface of the 

 carapace are so arranged that the pads can be lowered and pressed 

 against the skin of the host's bodj^ The adhesive surface of the 

 pad is formed of a thick cushion of skin whose outer layer is raised 

 into ridges similar to those in the epidermis on the palms of our 

 hands. These ridges are usually transverse, but are sometimes 

 arranged concentrically, as on the tips of our fingers. They seem to 

 serve the same purpose on these pads that they do on our hands — the 

 development of friction and the prevention of slipping. 



The claws or chelae are found on the tips of the second maxillipeds, 

 which are the chief organs of prehension. In the males of all the 

 genera and in the females of some of them the second maxillipeds 

 end in curved claws similar to those found in the Caliginse and 

 Euryphorinas. 



Fig. 2.— Ventr.vl surface of 

 FEMALE Pandarus sinuatus, 



SHOWING ADHESION PADS. 



