PACKARD.] MORPHOLOGY OF PHYLYOPODA. 393 
Except the diminished size of the gill, the only other important modi- 
fication in the foot is the large triangular sixth endite, which shares in 
part the enlargement of the subapical lobe. 
In the Branchipodide, where the head, thorax, and abdomen are clearly 
differentiated, all the legs are thoracic, there being no abdominal ap- 
pendages except the gonopoda and the cercopoda. The legs also differ 
much more from the two lower Phyllopodous families than those of the 
members of these two families from each other. The axial relations of 
the Branchipod limb are much as in the Limnadiada, the axis being not 
only entirely without any traces of joints, but not differentiated in any 
such way as in the Apodide from the endites or exites; in this respect 
the limb corresponds to those of the Limnadiada. The chief difference, 
however, from the two lower families is the absence of a functional 
gnathobase. The basal or first endite, as seen in the figures on Plates 
VIII-XIV, forms a very short and broad uniformly curved lobe with no 
armature at the base, the edge being uniformly fringed with very long, 
delicately setulose setz; the lobe is weak and only adapted for swim- 
ming. By reference to Plate XIV, fig. 4, it will be seen, as in the genus 
Thannocephatus, that the sternal groove along the under side of the body 
is broad, that the endites on either side are quite remote from each other, 
so as to be of little use in retaining the food or prey. This figure also 
shows the relations of the endites to the leg or axis, and of the leg as a 
whole to the body. The second endite is in general about one-third as 
wide as the first, while the third and fourth are minute, more or less 
pointed, and provided with three or four long setulose or ciliated sete. 
The great size and breadth of the fifth and sixth endites constitute a 
characteristic and diagnostic feature of the family. The fifth is very 
large and squarish or rounded, and armed on the edge with short re- 
mote spines. The sixth is more or less paddle-shaped, subtriangular, 
and provided with a fringe of very long and rather stiff setie; being well 
adapted for use in swimming; this lobe, with the fifth, is mainly con- 
cerned in locomotion. The two exites, the flabellum and gill, are in 
this family much more alike than in the other two groups. The gill (br) 
in Artemia, Branchinecta, Branchipus is small, oval in outline; and much 
as in the Apodide, but in Chirocephalus, and especially in Streptocepha- 
lus, it becomes much larger, while in Thamnocephalus it is much like the 
flabellum (br’) in size and form as well as in structure. 
It is interesting to observe, from the drawings of Claus and of Gissler, 
that in the development of the legs in the early larval stages the endites 
are the first to be developed, the exites not appearing until some time 
after the six inner lobes are indicated. 
The abdomen and the abdominal legs (Uropoda).—These are not present 
in the Granchipodide, and in the Limnadiade and Apodide they do not 
whole of the abdomen not covered by the shield over the edge of the carapace of the 
female to her ventral side. These motions were wholly similar to those made by the 
male Branchipus with its body during sexual congress, so that Ihave no doubt that the 
smaller individual was the male, and that the whole performance was none other than 
the fertilization of the gill-foot. The male repeated this act upon all the other 
females present through a period of several days. Then a pause ensued, whereupon 
the exhibition began anew. 
During the act of copulation the egg-sac of the 9 came in contact with the 11th 
feet of the ¢; but the whole occurrence was so short, the animals going under and 
turning themselves several times, that it was difficult to give a clear idea of the rela- 
tion of the body parts to one another. 
Through a later anatomical examination of the male I found my view completely 
confirmed. It was filled abundantly with testes-tubes, finger-shaped, the branches 
filled with seminal cells, as were described by Kozubowski. He then quotes Kozu- 
bowski’s similar observations on the mode of copulation, from which Brauer’s obser- 
vations differ somewhat. 
