PARASITIC COPEPODS — WILSON 557 



margin of the fourth basipod in the male. When this copepod is alive 

 it must be highly colored, as even in the preservative the thorax re- 

 tains a deep orange hue and the carapace and abdomen have a bluish 

 tinge, probably a bright blue in the living copepod. 



ARGULUS LUNATUS, new species 



PiATE 23, FiGUBES 57-63 ; Plate 24, Figures 64-66 



Eight females and four males were obtained from the outside sur- 

 face of goldfish {Carassius auratus) at Norfolk, Va. One female and 

 a male have been designated the holotype and allotype, U.S.N.M. No. 

 78893. 



Female. — Carapace broadly elliptical, somewhat narrowed ante- 

 riorly, with wide posterior lobes that reach the anterior margin of the 

 abdomen. Posterior sinus broad and flaring, one-third the carapace 

 length and squarely truncated at its base. Cephalic area 58 percent 

 of the carapace length ; eyes large and far forward but well separated. 

 Eespiratory areas elongate-elliptical, the anterior one much smaller 

 than the posterior and the two in contact along a transverse line. The 

 four thoracic segments are all the same width and the first three are 

 the same length, while the fourth is shorter but is not narrowed poste- 

 riorly. The abdomen is obovate, longer than wide with broadly 

 rounded anterior corners and narrow posterior lobes bluntly rounded 

 at their tips. The sinus does not reach the center of the abdomen, and 

 the caudal rami are lateral, each mounted on a shoulder near the base 

 of the sinus. The seminal receptacles are circular, of medium size, 

 and widely separated close to the anterior corners. 



The first antennae are narrow and elongate, the two proximal 

 segments fused, with no spine at their base or on the posterior margin, 

 but with a short and stout spine on the anterior margin. The lateral 

 claw is curv^ed into a half circle and reaches the tip of the flagellum. 

 The second antennae are 5-seg-mented, the two basal segments enlarged, 

 the end segment lanceolate. The supporting rods of the sucking 

 disks are made up of seven or eight elliptical segments gradually 

 diminishing in size distally and tipped with a twisted rod. The basal 

 segment of the maxilliped is stout and longer than the three distal 

 segments combined, the basal plate is wide and the three spines are 

 short, stout, and blunt. The raised area is covered with coarse spines 

 and smaller spines are scattered over the entire ventral surface of 

 the appendage. The first two pairs of legs have flagella and the two 

 basipod segments of all four pairs are more or less completely fused. 

 In the fourth legs the part corresponding to the proximal basipod 

 segment is prolonged backward into a flap, which is broadly rounded 

 at its tip and fringed with hairs but bears no resemblance to a boot, 



