eat INTERNAL ANATOMY OF PHYLLOPODA. 399 
remarks further on, and to the explanation of the plate. In fig. 2 
(Artemia, drawn from living specimens) the ovaries are without any 
ovarian eggs, the cells representing simply the epithelium. The ovary 
sends two slender attachments into the last benomere, and two larger 
tubular prolongations into the second and third uromere. The oviducts 
(e) are just large enough to contain a single egg (Fig. 2b, egg) at one 
time. The glandular cells secreting the chorion are represented at 2a 
and 2b, ec. They are about }-% the diameter of the mature egg, and 
have a very distinct nucleus. 
The heart.—In the Limnadiade the heart of Limnetis is a short, thick 
tube, as represented by Grube (see our Plate X X XJ, fig. 6, ht), and does not 
extend far back in the body. In the section of Hstheria mexicana (Plate 
XXIV, fig. 9), which passes through the antenne, the heart is seen to 
be present, but in H. compleximanus, fig. 10, it does not appear to reach 
far behind the anterior pairs of beenopods. 
In Apus the heart has been figured and described by Zaddach, our 
fig. 6, Plate XX XII, being copied from his work, and in our fig. 1 the 
heart is represented diagrammatically, the drawing not being strictly 
accurate in some respects. The size of the heart of Apus lucasanus in re- 
lation to that of the intestine is seen in fig. 2, which is a camera draw- 
ing. The walls are thick and muscular. 
In the Branchipodide the heart is much larger than in the Apodide, 
as seen in Plate XXIII, figs. 2, 3, 3a, and 4, drawn with the camera 
from living specimens of Artemia gracilis. The heart extends from a 
point just below the mandibles, and extends as a long, slender tube to 
the middle of the terminal uromere. In fig. 2 the anterior end of the 
heart is represented conjecturally, as we could not see the exact mode 
of termination or the origin of the arteries; * but the valve at the pos- 
terior end was readily made out as at 3, ht, and 3a, where a treble 
valvular arrangement allows the blood to enter, and is closed at the 
time of contraction of the heart. Two lateral arteries are sent off to 
the shell-gland, and there is a median notch or ostium in front. The 
lateral valvular openings are more numerous in front than at the end, 
as the last pair of valvular openings is situated a long distance from 
the end of the heart, as seen in fig. 3. As seen in fig. 4, the heart is 
loosely held in place by slight muscular bands (m), and along the 
outer walls of the heart are scattered rounded epithelial cells (ep. c). 
The valvular openings, indicated in the figures by the arrows, are 
arranged alternately. The size of the blood-corpuscles, which are 
colorless, is shown in the figure. The blood flows into the heart 
through the valvular openings, and is pumped out of the anterior 
end and passes into the head by two currents, while a current on each 
side passes backward, thus indicating the existence of two anterior 
arteries and a pair extending downward and backward. The circula- 
tion in the eye is readily observed, and is indicated by the blood- 
corpuscles and arrows in fig. 6. The mode of circulation in one of the 
feet is illustrated by the blood-corpuscles and arrows in fig. 7 (Pl. 
XXIII). The blood flows directly toward the end of the sixth endite, 
while a portion passes around the edge of the gill; the circulation is 
more active in the gill proper than in the flabellum. The blood passing 
into the sixth endite along the upper side, returns by the lower edge: 
a current, entering the fifth endite, passes along the upper and returns 
by the lower edge; a current also enters the basal endites. Each 
* The anterior end of the heart in the young Apus is well shown by Claus in fig. 6, 
Tat. VIU, of his elaborate memoir. 
