282 
Holotkuria atra 
nearly closed the opening is a narrow slit. In sections it is seen that beneath the 
blind bottom of the funnel-shaped pit (Fig. K) there is a closed lacunar space, 
sometimes spherical, but more frequently drawn out into an elongated canal- 
like space {I). The sections show the characteristic loosely woven connective tissue 
fibres and the spaces (s) from which spicules like the tables in (Fig. J) have been 
dissolved. Fisher (1907) seems not to have noticed my preliminary paper (1905) 
in which these pits were first mentioned, and hence has failed to include in his 
description these and some of the other characters by means of which I have 
clearly differentiated H. atra from H. floridana. 
F. Calcareous Spicules of the Body-wall. 
The spicules are not so numerous as in H. floridana and the warts found in 
that species do not occur. 
a. Tables. 
For the general description of the development, structure and variation of the 
tables there is no distinction to be made from H. floi^idama (cf. p. 256 et seq.). 
b. Tables of Bivium and Trivium in H. atra. 
For this study data were taken from 16 specimens collected all the way from 
the Hawaiian Islands to Mozambique. Ordinarily 10 tables were taken from each 
TABLE XXXIV. 
Tables of Bivivm and Ti'iviiim. 
Disc 
Crown 
Number 
of Peri- 
pheral 
Holes 
Number 
of 
Spines 
Diameter 
Height 
M- 
Number 
of 
Teeth 
Diameter 
of Hole 
Diameter 
not includ- 
ing Teeth /x 
Diameter 
including 
Teeth fx. 
Dor-al 
Mean 
Standard 
Deviation 
Coefficient of 
Variation 
Range of 
Variation 
3-740 
+ -069 
1 -2.57 
+ -049 
31 -008 
± 1 -208 
0—9 
-713 
+ -097 
1-753 
+ -083 
245-65 
± -957 
0—10 
47-927 
+ -251 
4-558 
+ -178 
9-511 
±3-704 
35-2—60-8 
65-870 
± -590 
9-780 
+ -416 
14-840 
± -024 
41-92—92-22 
11-960 
+ -055 
-999 
± -039 
8-355 
± -325 
8—15 
9-225 
+ -148 
2-637 
+ -105 
28-580 
±1-136 
3-2—19-2 
19-710 
-1- -156 
2-779 
+ 1-101 
14-100 
± -569 
12-8—25-6 
44-030 
+ -300 
5-4.39 
± -212 
12-350 
± -500 
32-0-57-6 
Ventral 
Mean 
Standard 
Deviation 
Coefficient of 
Variation 
Range of 
Variation 
3 -.578 
+ -094 
1 -652 
+ -066 
46-100 
± I -845 
0—9 
-669 
+ -094 
1-667 
+ -068 
249-07 
± -997 
0—9 
44-603 
+ -326 
5-763 
+ -231 
12-920 
±5-199 
28-8—60-8 
47-629 
± -449 
7 -355 
+ -318 
15-432 
± -068 
31-1—70-0 
12-162 
+ -063 
1-117 
+ -045 
9-187 
± -367 
8—15 
9-190 
+ -155 
2-709 
+ -110 
29-476 
±1-192 
3-2—16-0 
18-780 
+ -150 
2-626 
± -106 
14-000 
± -577 
12-8—28-8 
38-756 
-1- -.337 
5-953 
+ -238 
15-350 
± -623 
25-6—57-6 
