266 E. A. ANDREWS 
the shorter base about 2mm. The bony rims of the triangle as 
seen in fig. vi may be called the humerus and the radio-ulna. 
The distal free part of the apparatus, (figs. v1, vir) is a tri- 
hedral mass set with long plumose setae and might be likened to a 
sort of hand at the end of the fore-arm. We will call it the wedge 
from its appearance and use as seen in sections (fig. 9). 
The humerus articulates at each end; proximally loosely with 
the side of the exodopodite mass, (fig. v1); distally at the elbow, 
firmly with the other firm edge of the triangle, the radio-ulna. 
On the external or concave face of the triangle, (fig. vit) the hu- 
merus is not as well separable from the membranous part of the 
triangle, and between its proximal end and the bone of the main 
mass of the endopodite there is more or less expanse of membrane. 
On this outer face, (fig. vimr) we find that all the concave aspect 
of the triangle is membranous. 
The humerus is wide and smooth and flat on the inner face, 
fig. v1, but on the outer face forms only a narrow edge to the mem- 
brane, fig. VIIt. 
The soft hollow face of the triangle in lifeis swollen with contained 
liquid. The soft area is not only the outer face of the triangular 
protuberance but also half of the dorsal face of the distal part of 
the main trunk of the endopodite. 
The whole darkened area of fig. vi11 might be compared to the 
soft inside of the palm of a hand and it is this which comes against 
the neck of the first stylet, in conjugation. 
While the humerus is wider toward the base and slender at 
the elbow end, the radio-ulna is the reverse; that is, it begins nar- 
row at the elbow and widens to the hand or terminal part.. The 
radio-ulna is a thick plate-like mass that is not in the same plane 
as the humerus, but about 45° with it, so that it has the appear- 
ance of a scroll rolling in over the depressed membranous outer 
face of the triangle, (figs. viz, vit). The radius part is the free 
rounded edge, (fig. vit) and this ends abruptly opposite the base 
of the hand, which is back of it in the figure, while the ulna plate 
runs on continuously in the background of this figure and passes 
imperceptibly into the hand, or wedge, (fig. viz). 
The radius stands free, away from the membrane, as a rounded 
