. The Cambridge natural history. Zoology. 40 CRUSTACEA BRANCHIOPODA patch () of columnar ectoderm, containing concretions like those described in the Branchipodidae, and behind this is a pair of cup-shaped organs (), with raised margins. The fold of skin which forms the carapace contains the coils of the single pair of kidneys, and it forms an important organ of respiration, partly from the great size of the blood-vessels it contains, and partly from the presence of red, blue, or brown respiratory pig- ments in the tissue of the skin itself. In most Cladocera the cuticle of the carapace
. The Cambridge natural history. Zoology. 40 CRUSTACEA BRANCHIOPODA patch () of columnar ectoderm, containing concretions like those described in the Branchipodidae, and behind this is a pair of cup-shaped organs (), with raised margins. The fold of skin which forms the carapace contains the coils of the single pair of kidneys, and it forms an important organ of respiration, partly from the great size of the blood-vessels it contains, and partly from the presence of red, blue, or brown respiratory pig- ments in the tissue of the skin itself. In most Cladocera the cuticle of the carapace is cast at every ecdysis, with that of other parts of the body; but in lliocryptus and a few others it remains after each moult, giving the carapace an appearance of " lines of growth," like that seen in many Limnadiidae. The segmentation of the body behind the head is obscure, but we can generally recognise (1) a thorax, of as many segments as there are pairs of limbs; (2) an abdomen of three seg- ments ; and (3) a telson. The thoracic limbs of the Calypto- mera are flattened, and resemble those riG. 11.—Sida crystallina, male, i -i-ii n X 27. Oxford. , El on- of the Phyllopoda; as a type we may gated first antenna; examine the third thoracic limb of paired element oi dorsal organ; ^, median element SimOCephciluS (Fig. 12, C), ill which of dorsal organ ; Te, testes ; ^^ • ^ ^ ^ gnathobase 6, opening of vas deferens. _ c? o (Gn) on its inner edge, followed by two small endites; the terminal process, or exopodite (Ux), is a large flattened plate, with six long plumose hairs on its edge. The outer margin of the axis bears a bract (Br) and an epipodite. In Simocephalus, as in the other Daphniidae, there are five pairs of thoracic limbs, of which the third and fourth are alike; in the female each limb of the first pair consists of a jointed axis, with strong biting hairs on the inner border, and a rudimentary epipodite (Fig. 12, A), the second limb being mor
Size: 1100px × 2270px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorsh, bookcentury1800, bookdecade1890, booksubjectzoology
