AET.5. NORTH AMEEICAN PARASITIC COPEPODS WILSON. 43 



SpecifiG characters of nauplius. — General form ovate, nearly twice 

 as long as wide, widest through the bases of the third appendages, 

 narro^ved posteriori}^, with evenly curved lateral margins. Ap- 

 pendages long and slender. Eye double and situated so far forward 

 as to touch the anterior margin. Balancers close to the posterior end 

 of the body, long and slender, with a slight S curve, extending 

 outward nearly at right angles to the body axis. On each lateral 

 margin in front of the base of the balancer is a small but distinct 

 notch. 



General color brown, the food mass in the posterior portion of the 

 body and the central digestive tract a very dark brown, the margins of 

 the body and the muscles connected with the appendages much lighter 

 in color, the appendages themselves and the balancers a light gray. 



Total length, 0.35 mm. Greatest width, 0.19 mm. 



Remarks. — This nauplius may be distinguished from that of 

 hrevoortiae by the length and narrowness of the body, by the greater 

 relative length of the appendages, and by the presence of eyes, or 

 rather of a compound eye, on the anterior margin. The color is 

 also quite different in the two nauplii, especially by transmitted 

 light. 



LERNANTHROPUS BREVOORTIAE Rathbun. 



Plate 7, figs. 51-55, 57 ; plate 8, figs. 58-60 ; plate 10, fig. 75. 



Lernanthropus brevoortiae R. Rathbun, Proc. U. S. Nat. Mus., vol 10, 

 1887, p. 563, pi. 30, figs. 7 and 8, pis. 31 and 32.— M. J. Rathbun, Occa- 

 sional Papers, Boston Soc. Nat. Hist., vol. 7, 1905, p. 97. 



Host and record of specimens. — ^Mr. Richard Rathbun obtained 

 about 50 specimens, all females, from the gills of menhaden, Bre- 

 voortia tyrannus^ captured in Vineyard Sound in 1883 and 1885. 

 The following specimens have been added to the Museum collection 

 since his paper was published, all from the same host: Six females 

 captured at Woods Hole, Massachusetts, September 3, 1904, with 

 Cat. No. 54052, U.S.N.M. ; 35 females, most of them very small, and 

 a single male from the gills of several young fish only 4 inches long 

 at Beaufort, North Carolina, August 10, 1905, with Cat. No. 54054, 

 U.S.N.M.; 15 females, some of which are still fastened to the gill 

 filaments, taken at Woods Hole, Massachusetts, August 6, 1901, with 

 Cat. No. 54053, U.S.N.M. ; 10 females taken July 20, 1905, at Woods 

 Hole, Massachusetts, with Cat. No. 54056, U.S.N.M. ; 2 females taken 

 July 20, 1905, at Beaufort, North Carolina, with Cat. No. 54055, 

 U.S.N.M. These records, with those of Rathbun, show that the 

 species is quite common along our Atlantic coast, but thus far only a 

 single male has been obtained, and yet diligent search for males was 

 made at Woods Hole during the entire summor of 1903 and at 

 Beaufort during 1905. Finally a school of very young menhaden 



