. A manual of zoology. Zoology. 37S ARTHROrODA i;ill chamber being modified into a kind of lung tra\-ersed l\v numerous blood-vessels. In the palm crab (_lig. 300) the gill chamber is di\-ided into two portions, the upper part being pulmonar\-, the lower containing the reduced gills. Correlated to this localized respiration is the nearly closed circulatory system [hg. 400, .1, B). The heart (/;), a compact pentagonal organ, receives its blood from the pericardial sinus (pc) through three pairs of ostia, and forces it out through live arteries to the capillary regions of the body. The venous bl
. A manual of zoology. Zoology. 37S ARTHROrODA i;ill chamber being modified into a kind of lung tra\-ersed l\v numerous blood-vessels. In the palm crab (_lig. 300) the gill chamber is di\-ided into two portions, the upper part being pulmonar\-, the lower containing the reduced gills. Correlated to this localized respiration is the nearly closed circulatory system [hg. 400, .1, B). The heart (/;), a compact pentagonal organ, receives its blood from the pericardial sinus (pc) through three pairs of ostia, and forces it out through live arteries to the capillary regions of the body. The venous blood collects in a large venous sinus at the base of the gills (f). passes thence through gills, and is returned by several brancliial veins {I'br) to the pericardium. pdiM plbrt. Fig. 3qS.—Gills of .»,t exposed bv cutting away the brancliiosteeiitc. pjh. plh, podo- and pieurobranchia of the corresponding segments; r, rostrum; t. stalked eyes; 2, 3. antenna;; 4-6, mandibles and ;; 7-9, ; 10, 14. bases of thoracic eet; 15, first pleopod. The ahmentary canal is straight and has only one conspicuous enlarge- ment, the so-called stoDiacli (tig. 400, .1, in), divided ii^to two portions, an anterior [cardiac) sac, lined with chitinous folds and teeth and serving to chew the food and bearing in its walls the 'crab-stones,' masses of calcic carbonate stored up to harden the armor rapidly after the molt. The second (pyloric) portion of the stomach is guarded by hairs and serves as a strainer, allowiitg only food sulliciently comminuted to pass. The two liver lobes—voluminous masses of branched glandular tubes (/) open just beliind the stomach. The two antennal glands [C. i^d), each provided with a large urinary bladder (M), are dirty green iti color, whence the name green glands often given them. The gonads (fig. 401) lie close beneath the heart, those of the two sides being united liehind, while their ducts remain separate. The structure of the nervous syste
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
