A MERICAN PA RASITIC COPEPODS— WILSON. 717 



Pandarina?. Second maxilla? bifurcate at the tip; first niuxilhe and 

 furca wanting. All four pairs of swimming legs hiramose: rami of 

 the first pair two-jointed, of the other pairs three- jointed; jointing, 

 spines, and setse almost exacth- like those in Treblus. 



{dissomis^ disagreeing or different; i. e., a connecting link which 

 does not agree with an}^ of the established subfamilies.) 



DISSONUS SPINIFER Wilson 

 Plate XX, tigs. 71-72. 

 Dissonus splnifer Wilsox, 1906, p. 198, pi. in, figs. 34-47. 



Female. — Carapace transverseW semilunar, twice as wide as long; 

 dorsal surface with but a single pair of grooves, separating the lateral 

 areas fi-om the cephalic. Eyes moderately large, close to the anterior 

 margin; in contact with each other on the mid-line, but not fused. A 

 pair of elliptical spots in front of the eyes raised like lenses. Second, 

 third, and fourth segments diminishing regularly in size; second seg- 

 ment as wide as the carapace and its lateral plates as wide as the lateral 

 lobes of the carapace. Third and fourth segments considerably nar- 

 rowed, but ev^en the fourth twice as wide as long. Genital segment 

 quadrangular, a little wider than long and a little narrower than the 

 fourth segment; posterior processes small, fifth legs invisible dorsally. 

 Abdomen three-eighths the length of the genital segment, one-fourth 

 wider than long, with a shallow anal fissure. Anal lamina? (juadran- 

 gular, each with four large plumose setfe, three of which are terminal, 

 while the other comes out of the lateral margin near the anterior end. 



The two pairs of antennte like those of ( '(fh'gus: first maxilUe and 

 furca entirely lacking; mandibles slender, three-jointed, toothed on the 

 inner margin near the tip. 



Mouth-tube triangular with a narrow tip; mouth-opening terminal 

 and heavily fringed with hairs. Second raaxillse large and powerful, 

 reaching well beyond the tip of the mouth-tube;" ba.sal portion enlarg-ed 

 and flattened, bearing the rudimentar}^ exopod; endopod triangular and 

 curved, bifurcate at the tip, the outer branch a little the larger and 

 longer. The two pairs of maxillipeds of the usual pattern, the basal . 

 joint of the second pair with a stout corrugated knob against which 

 shuts the tip of the terminal claw. In the first pair of swimmmg legs 

 the exopod is a little more than twice the length of the endopod. and 

 its basal joint is three times as long as the terminal. The endopod 

 joints are about the same size. The other swimming legs as in the 

 Trebinpe and other Euryphorintx?, the fifth pair as small papilla\ each 

 armed with three seta?. 



Cement glands small, broadly club-shaped, and reaching but little in 

 front of the center of the genital segment. 



