334 



Gen. 77. RobertSOIlia, Brady, 1880. 



Generic Characters. Body not depressed, almost cylindric in form, though 

 tapering behind, with no very sharp demarcation of the 2 divisions. Rostrum 

 prominent, well defined behind. Genital segment imperfectly subdivided in female. 

 Caudal rami short. Anterior antennae comparatively short and stout, with the 

 number of joints somewhat reduced; those in male distinctly hinged. Posterior 

 antennae with the proximal joint not subdivided, outer ramus well developed, 

 though composed of only 2 joints. Oral parts normal. 1st pair of legs only 

 slightly differing in structure from the 3 succeeding ones, inner ramus 3-articulate 

 and about the length of the outer; inner ramus of 2nd pair of legs in male 

 conspicuously transformed. Last pair of legs of normal appearance, with both 

 joints well defined. 



Remarks. This genus was established in the year 1880 by Prof. Brady, 

 and was referred by that author to his sub-family Tachidnn j . I am also of 

 opinion, that this genus is more properly referable to the present family, although 

 the general form of the body is rather unlike that in the typical genus Tachi<r//i*. 

 Only one species has as yet been observed. 



214. Robertsonia tenuis, Brady. 



(PI. CCXXII). 

 Robertsonia tenuis, Brady, Monogr. of Bi-it. Copepoda, Vol. II, p. 25, PI. XLI, tigs. 1 



- 



Specific Characters. Female. Body moderately robust, somewhat dilated 

 in front, and rapidly tapering behind. Cephalic segment large and deep, fully 

 equalling in length the 4 succeeding segments combined ; rostrum rather prominent 

 and narrow triangular in form, tip obtusely acuminate. Epimeral plates of the 

 3 succeeding segments well developed and acutely produced at the posterior 

 corner. Last pedigerous segment almost as broad as the preceding segment. 

 Urosome somewhat exceeding half the length of the anterior division, and gradually 

 tapering distally, posterior edge of the segments coarsely spinulose, genital segment, 

 fully as long, as the remaining segments combined. Caudal rami broader than 

 they are long and obtusely truncated at the end, edges partly spinulose, apical 

 setse of moderate length and normal structure. Eye distinct though rather small. 

 Anterior antennae much less than half the length of the cephalic segment, 

 and rather densely clothed with comparatively short, partly ciliated setse, being 

 composed of 5 joints only, 3 of them belonging to the proximal part, terminal 

 part about half the tength of the latter, with the 1st joint very small. Posterior 



