no. 1404. PARASITIC COPEPODS—CALIGID.E— WILSON. 619 



basal joints are thick and swollen, and they reach nearly to the center 

 of the genital segment, while the three terminal joints, much narrower, 

 extend well beyond the tips of the anal papilla?. There are the usual 

 five spines on these legs, arranged in the customary manner. There 

 are several species (erecsoni, hippoglossi, nordmannii, etc.) in which the 

 fourth legs of the male reach beyond the tips of the anal papilla 3 , but 

 this is the first instance where the same is true of the female. Fur- 

 thermore, these legs in the present species are far larger than those 

 of any known male, the basal joint on each leg being actually larger 

 than the entire free segment to which it is attached. 



This, therefore, may be taken as the distinguishing characteristic of 

 the species. 



Total length 8.5 mm. Length of carapace 4.25 mm.; width of the 

 same 3.6 mm.; length of genital segment 2.1 mm.; length of abdomen 

 1.25 mm.; length of egg strings 7 mm.; length of the fourth legs 4.2 

 mm., including the spines. 



The color in preserved specimens is a dark yellowish gray, without 

 any pigment visible. 



(longipes, longus, long, and pes, foot.) 



This species is very clearly differentiated from all otheiM by the size 

 of the fourth legs, bj T the shape of the f urea, and by the curved claw 

 on the endopod of the second legs. 



The National Museum collection unfortunately includes only a single 

 unnumbered lot of two females, and there are no data as to the locality 

 or the host from which they were obtained. 



LEPEOPHTHEIRUS THOMPSONI Baird. 

 Plate XVIII, figs. 212-219. 



Lepeophtheirus thompsoni Baird, 1850, p. 278, pi. xxxm, fig. 2. — White, 1850, p. 



121.— Bassett-Smith, 1899, p. 455.— T. Scott, 1900, p. 152, pi. v, figs. 43-45. 

 Caligus gracilis P. J. van Beneden, 1851, p. 90, pi. n, figs. 1-7; 1861, p. 147.— 



Richiardi, 1880, p. 148. 

 Caligus branchialis Steenstrup and Lftken, 1861, p. 362, pi. ii, fig. 3. — Claus, 



1864, ]>. 365, pi. xxxm, figs. 3-7; pi. xxxiv, figs. 8 and 9. 

 Lepeophtheirus rhombi Kroyer, 1863, p. 118, pi. v, fig. 5, a-i. 

 Lepeophtheirus gibbus Kroyer, 1863, p. 121, pi. xvn, fig. 2, a-i. 

 Lepeophtheirus gracilescem KkGyer, 1863, p. 124, pi. vi, fig. 2, a-i. 

 Lepeophtheirus gracilis Carus, 1885, p. 359.— Brian, 1898, p. 12, pi. i, fig. 5; 



L899, p. 3. 

 Lepeophtheirus obscurus Bassett-Smith, 1896, a., p. 157; 1896, ]>., pi. iv, fig. 2. 

 Lepeophtheirus branchialis Bassett-Smith, 1899, p. 456. 

 Lepeophtheirus obscurus T. Scott, 1900, p. 153, pi. vi, figs. 16-19. 



Female. — Carapace obovate, a little wider than long, not much nar- 

 rowed anteriorly. Frontal plates narrow but distinct, without airy 

 incision at the center. Posterior sinuses widely triangular and shal- 

 low, leaving a median lobe less than half the entire width and not pro- 

 jecting beyond the lateral lobes. 



