C. L. Edwards 
265 
a. Form. 
The typical pedicel is cylindrical (PI. III. Fig. 2), and the papilla conical 
(Fig. 1). In this species the form of the 88 appendages of the bivium studied is : 
cylindrical, 49 (55-7 7o); conical, 4 (4-5 7 J ; not determinable, 35 (39-8 7 J. In 
the trivium all are cylindrical. 
b. Suckers. 
The presence of a fundamental sucker is the chief and necessary character of 
the pedicel. In 73 (83 °/^) of the dorsal appendages the sucker is present, in 
2 (2-3 7J rudimentary, in 4 (4-5 7J absent and in 9 (10-2 °/J not determinable. 
In all of the ventral appendages a well-developed sucker is present. 
c. End-plates. 
With but one exception the ambulacral appendage has at least some trace of a 
perforated plate, or a rosette, as the end-plate. One dorsal case was not deter- 
minable. In the pedicel the end-plate is large and located in the base of the 
sucker (seen in profile in Plate 11. Fig. 2). 
TABLE XXI. 
Diameter of End-plates in fi. 
Dorsal 
Ventral 
Type 
Type 
A 
B 
C 
B 
A 
B 
C 
Frequency 
Mean 
Standard Deviation ... 
Coefficient of Variation 
Range of Variation . . . 
41 (47-7 7J 
540 'OS:} 
+ 9-632 
91 -436 
+ 6-811 
16-900 
+ 1 -270 
435—750 
36 (41 -9 7 J 
354-677 
+ 5-676 
50-486 
+ 4-013 
14-230 
+ 1-130 
225—420 
8(9-37J 
182-380 
+ 5-195 
21-786 
+ 3-674 
1 1 -940 
+ 2-020 
120—195 
1(1 -iVo) 
90-000 
46 (927J 
701-260 
+ 13-785 
138-545 
+ 9-743 
19-750 
+ 1-380 
450—975 
3 (6 7 J 
288-000 
+ 9-927 
25-493 
+ 7-020 
8-850 
+ 2-430 
255—315 
1 (27o) 
210-000 
The most completely developed end -plate I have called Type A. It is nearly 
circular and has immerous holes varying in size (Fig. 3). In some cases the holes 
are less uniform with larger holes toward the centre (Fig. 4). Type A has a mean 
diameter of 541 with a range of 435 — 750 /a dorsally. In the trivium Type A 
is larger, having a mean diameter of 701//. with a range of 450 yu. — 975 yu.. This 
type occurs in 48 of the dorsal appendages and in 92 '/^ of the ventral. 
Type B (Fig. 5) has a mean diameter of 355 fx with a range of 225 /a — 420 
dorsally and therefore it is something over lialf the size of Type A in this region. In 
Biometrika vi 34 
