NO. 1404. PARASITIC COPEPODS—CALIGID.E— WILSON. 621 



Total length 8.4: mm.; length of carapace 3.2 mm.; width of same 

 3.4 mm.; length of genital segment 2.8 mm.; length of abdomen 2.1 

 mm.; length of egg strings 8.5 mm.; 125 or 180 eggs in each. 



General color a light yellow, the hard parts turning much darker on 

 preservation. 



(f/w?npsoni, to William Thompson, who did much valuable work on 

 the Irish fauna.) 



JIfde. — Carapace elliptical, one-sixth longer than wide, with evenly 

 rounded sides. It is twice as long and nearl}^ three times as wide as 

 the rest of the body. The posterior sinuses are shallow and consider- 

 ably narrower than in the female, but the grooves and general propor- 

 tion of the parts are the same. . 



The free segment is more than half the width of the genital segment 

 and is swollen at the center through the bases of the fourth legs, so 

 that it becomes spindle-shaped. 



The genital segment is orbicular, of about the same length and width, 

 one-third the length of the carapace. It carries two pairs of setiferous 

 papillte, one on the lateral margins near the posterior corners and the 

 other pair at the corners. 



The posterior margin between the latter papilla^ is slightly concave. 

 The abdomen is half the length of the genital segment, a little longer 

 than it is wide, and strongly narrowed at the base. The anal lamina 

 are minute and carry small setie. In the appendages there is the usual 

 increase in the size of the second antenna and second maxillipeds; 

 otherwise the appendages are like those in the female. 



Total length,! mm. Length of carapace, 2.8 mm.; width of the 

 same, 2.4 mm.; length of genital segment, 0.7 mm.; length of abdo- 

 men, 0.4 mm. 



The specimens of this species in the possession of the National 

 Museum were obtained from Rev. A. M. Norman. The lot is num- 

 bered 8032 and consists of females onl}^, taken from the turbot, Rhom,- 

 hufi mcci-iinus, at Cornwall, England. 



In all probability this is the species referred to by S. I. Smith (1874, 

 p. 281) as found on the sting-ray {Dasyatis centrurd) in Vineyard 

 Sound; but those specimens were not preserved, and none have since 

 been obtained from the same lish. 



But during the past season the author received from Mr. V. N. 

 Edwards a single female of this species taken from a goosefish at 

 Woods Hole. 



There has been the utmost confusion in the description of the species 

 of Le/peophtheirus infesting the common turl^ot and brill of European 

 waters. There are no less than seven species of this one genus, all 

 claiming to be valid and all infesting the same tish. These seven 

 species are as follows, given in the order of their discover}-: Lepeoiph- 

 theirus thompson'i Baird, 1850; gracilis van Beneden, 1851; hranch- 

 Proc. N. M. vol. xxviii— 04 40 



