PACKAKD.] 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 representiug simply the epithelium. The ovary 

 sends two slender attachments into the last bajnomere, 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 Limnadiadm the heart of Limnetis is a short, thick 

 tube, as represented by Grube (see our Plate XXXI, fig. 6, ht), and does not 

 extend far back in the body. In the section of Estheria mexicana (Plate 

 XXIV, fig. 9), which passes through the antenuse, the heart is seen to 

 be present, but in JE. compleximanus, fig. 10, it does not appear to rea>ch 

 far behind the anterior pairs of b^enopods. 



In Apys the heart has been figured and described by Zaddach, our 

 fig. 6, Plate XXXII, 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 A2ms 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 BrancMpodidce the heart is much larger than in the Apodidce, 

 as seen in Plate XXIII, figs. 2, 3, 'da, and 4, drawn with the camera 

 from living specimens of Artemia gracilis. The heart extends from a 

 point justbelow 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 coiijecturally, as we could not see the exact mode 

 of termination or the origin of the arteries j * but the valve at the pos- 

 terior end was readily made out as at 3, ht, and 'Sa, 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-ghmd, 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. G. The mode of circulation in one of the 

 feet is illustrated by the blood -corpuscles and arrows in fig. 7 (PI. 

 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 tlie heart in the young Apus is well shown by Glaus in fig. 6, 

 Tat". VlIIj of his elaborate memoir. 



