C. L. Edwards 289 
TABLE XXXVII. 
Polian Vesicles. 
Adult ; 12 Specimens 
Young ; 8 Specimens 
Number of 
Vesicles 
Greatest 
Length mm. 
Number of 
Vesicles 
Greatest 
Length mm. 
Mean 
Standard Deviation 
Coefficient of Variation ... 
Range of Variation 
20 -750 + 3 -835 
19-698 + 2-712 
94-930 + 6-325 
1—56 
17-000 + 1-639 
8-416+1-159 
49-505 + 6-816 
9—42 
9-500+ 1-460 
6-124+ 1-033 
64-458 + 10-869 
4—24 
13-250+1-299 
5-449+ -949 
41-121 +6-934 
8—21 
Pearson, 1903, p. 203, notes 3 specimens, each with one Polian vesicle. 
The mean number of Polian vesicles is 21, with a range of 1 — 50, in the adult 
and 10, with a range of 4—24, in the young. Ludwig, 1889-92, p. 115, gives the 
range as 1 — 10. The suiallest Holothurid, 1G7, has 10 Polian vesicles, and the 
smallest number any specimen has is 4. Thus H. atra shows a considerable 
difference from H. fluridana, in whicli 74 /^^ of the young have only one Polian 
vesicle. The mean greatest length increased from 13 mm. vvitli a range of 8 mm. 
— 21 mm. in the young, to 17 mm. with a range of 9 mm. — 42 mm. in the adult. 
J. Stone-canals and Madreporites. 
The stone-canals and madreporites agree in location and form with H. floridana 
(p. 271). In 16/^ most of the madreporites are fused. 
TABLE XXXVIII. 
Stone-canals. 
Adult ; 12 Specimens 
Young ; 8 Specimens 
Number 
Greatest 
Average 
Length 
mm. 
Number 
Greatest 
Length 
mm. 
Average 
Length 
mm. 
Eight 
Left 
Total 
Length 
mm. 
Right 
Left 
Total 
Mean 
Standard Deviation ... 
Coefficient of Variation 
Range of Variation . . . 
11-000 
+ 1 -433 
7-360 
+ 1-013 
66-906 
±9-212 
4—27 
12-000 
+ 1-769 
9-083 
+ 1-251 
75-692 
+ 10-421 
7-43 
24-084 
+ 2-933 
15-064 
+ 2-074 
62-547 
+ 8-612 
15—70 
9-500 
+ -744 
3-819 
+ -526 
40-195 
+ 5-534 
5—16 
7-117 
+ -428 
2-248 
+ -310 
31-594 
+ 4-.350 
4-5—11 
8-2.50 
+ -789 
3-307 
+ -558 
40-085 
+ 6-759 
1—13 
6-375 
+ -394 
1 -654 
+ -279 
25-937 
+ 4-374 
2—8 
13-250 
+ 1-155 
4-842 
+ -816 
36-540 
+ 6-162 
8—21 
4-750 
+ -426 
1-788 
+ -302 
37-644 
+ 6-348 
2—8 
4-325 
+ -623 
1-763 
+ -297 
40-700 
+ 6-875 
1—7 
Biometrika vi 
