126 bulletin: museum of compaeative zoology. 



genitals are fully developed, and equally so on each radial canal, of 

 which there are four. 



The nest stage represented by the formula, 1 ; 1 ; 1 ; ; the genitals 

 were atrophied on one of the radial canals and equally developed on 

 the others. Seventy-eight specimens of this stage, 49 females and 29 

 males. 



The next most frequent stage is that in which two adjoining genitals 

 are fully developed ; the others are of the same size, but less well de- 

 veloped ; that stage is represented by the formula 1 ; 1 ; 2 ; 2 ; Out of 

 the 1,146 specimens examined there were only 74 specimens of this 

 stage, of which 45 were females and 29 males. 



Next comes the stage in which only one of the genitals is fully de- 

 veloped ; the others are less so, corresponding to the formula 1 ; 2 ; 2 ; 2 ; 

 39 females and 27 males. 



In the order of frequency of occurrence comes : 

 Eucope with the formula 1 ; 1 ; 1 ; 2 ; — 28 females and 17 males. 



Then comes the stage in which the genitals were unequally developed : 

 20 females and 21 males. 



Next, 

 Eucope with the formula 1 ; ; ; ; — 24 females and 13 males. 

 « u cc 1; 2; 0; 0; — 15 " " 3 " 



1 . 2 • 2; 0; — 10 " " 8 " 



In specimens with three radial canals we observed only one specimen 

 in which the genitals were uniformly developed. On Plate III. are seen 

 (Fig. 1) a specimen in which one of the canals forks at the extremities of 

 the heart-shaped genitals, forming three primary segments of nearly 

 equal size extending to the centre of the disk, with a small sector cut 

 from the outer edge of two adjoining segments. 



Figure 4 of the same plate shows a specimen with three radial canals 

 and four genital pouches, but the canal which forks subdivides above 

 the genitals so near the centre of the disk as to subdivide the disk into 

 four nearly equal segments. 



A variation similar to that of Plate III. Fig. 1, for a three-rayed 

 Eucope, has been observed in a four-rayed Eucope (Plate III. Fig. 2), in 

 which the fifth sector is a comparatively small triangle cut out from the 

 periphery of two of the adjoining sections, extending to the centre of 

 the disk. 



In Figure 5 of Plate III. the forking of the four-rayed Eucope, taking 

 place nearer the centre of the disk, subdivides the disk into segments of 

 more uniform size, and it closely resembles a five-rayed Eucope. 



