AGASSIZ AND WOOLWOKTH : VAKIATIOXS IN EUCOPE. 



127 



In five-rayed Eucope only one specimen was observed with equally 

 developed genitals (Plate V. Fig. 1). Those figured on Plate VI., as 

 well as the others on Plates IV. and V., all show a very great range 

 of variation in their development. In two cases (Plate IV. Figs. 3, 6) 

 two of the genitals are wanting. 



In Plate VI., Figures 1 and 2 are those of two specimens with five 

 radial canals, both of which fork so near the base of the manubrium 

 as to divide the disk into six nearly equal segments. 



The accompanying table will show the other variations which have 

 been observed, and their frequeuc}-. 



1146 Specimens examined for Vakiations in the Development of the 

 Genital Oegans on each of the Four Radial Canals. 



With Three Radial Canals, or Three with Fork. 



1 ; 2 ; 3 ; 3 females, and 1 male. 

 1; 1; 1; 1; 2 " « i » 



1 ; 1 ; 1 ; 1 female. 

 1; 1; 0; 2 '■ 



With Four Radial Canals. 



* 447 

 49 

 45 

 39 

 28 

 20 

 24 

 21 

 19 

 15 

 10 



6 



5 



5 



4 



3 



3 



4 males. 



females and 175 males. 

 " 29 " 



29 



27 



17 



21 



13 



9 



7 



3 



• 1, fully developed genitals ; 2, genital smaller than 1 ; 3, genital smaller 

 than 2 ; 4, genital smaller than 3 ; 5, genital smaller than 4 ; 0, genital organ 

 absent. The semicolon (;) indicates the position of the radial canal. The — ■ — 

 indicates the forking of the radial canal. 



