ON DEVELOPMENT OF ATYEPHIRA COMPRESSA. 421 
posterior branch is divided into two points. A small, single- 
jointed appendage, feathered on both sides, is seen on the 
proximal end of the anterior branch as in the preceding stage. 
This appendage is lost in future stages. 
The first pair of maxillae (fig. 87) consists of a long piece 
with two lobes, the outer, or basipodite (fig. 87, bp.), bearing 
three setae, and the inner, or coxopodite {exp.) with four setae. 
On the outer border of it, somewhat proximal to the division 
of the lobes, a single-jointed palpus, or endopodite (fig. 87, en.), 
with two long feathered setae, is placed. 
The second pair of maxillae (fig. 88) is about as long as the 
first, but is much the broader. It is divided into an inner and 
an outer lobe. The former consists of a large endopodite (en.), 
beset with six rather short setae on its inner border ; a small 
basipodite (bp.) consisting of two lobes, both of which bear long 
setae, and a coxopodite (exp.), also divided into two lobes at its 
extremity, bearing setae. The outer branch of the second 
pair of maxillae is a large scaphagnathite ( sg .) beset with 
setae. 
The first pair of maxillipedes (fig. 89) consists of a broad 
basal segment, and two terminal ones. The outer branch (ex.) 
is considerably longer than the inner, and consists of two 
joints, bearing five long setae on its extremity. The inner 
branch (en.) is about two thirds the length of the outer. It 
consists of four joints, beset with a few setae on its inner 
border. The basal segment also bears short setae on its inner 
border. 
The second and the third pairs of maxillipedes are similar in 
structure to the first pair, except that the basal segment of the 
second pair of maxillipedes is less broad than that of the first 
pair, and that of the third is again less than that of the second, 
while the length of the entire appendage increases in the 
reverse order. 
Thoracic Appendages. — Four pairs of the rudiments of 
these appendages (fig. 85, amb. 1 — 4) are already formed, each 
presenting two lobes. The first pair is about half as long as 
the third pair of maxillipedes. Each of the two branches of the 
