. A text-book of invertebrate morphology. Invertebrates. TYPE ARAOHNIDA. 449 is unsegmented, as is also the abdomen, which is an oval, spherical, or sometimes irregularly-shaped region which narrows suddenly anteriorly so as to be much narrower than the cephalothorax. The chelicerse project somewhat in front of the cephalothorax and each consists of a broad basal joint and a terminal strong claw which may be flexed upon the basal joint, and has opening at its tip the duct of a poison- gland (Fig. 206, pg) which lies in the cephalothorax. The it m. Pre, spg 306.—Diagram of Stkuctueb of a Spider
. A text-book of invertebrate morphology. Invertebrates. TYPE ARAOHNIDA. 449 is unsegmented, as is also the abdomen, which is an oval, spherical, or sometimes irregularly-shaped region which narrows suddenly anteriorly so as to be much narrower than the cephalothorax. The chelicerse project somewhat in front of the cephalothorax and each consists of a broad basal joint and a terminal strong claw which may be flexed upon the basal joint, and has opening at its tip the duct of a poison- gland (Fig. 206, pg) which lies in the cephalothorax. The it m. Pre, spg 306.—Diagram of Stkuctueb of a Spider (after Letickart). ao = aorta. ce = cei-ebral ganglion. ch = chelicera. dg = digestive gland. gp = genital pore. hi = heart. lb = lung-book. mi = Malpigbian tubule. oc = eye. ov = ovary. pe = peilipalp. pg = poison-gland. rb = rectal bladder. rs = receptacuhim semiuis. s = stomach. sd = stomach diverticulum. sp = spinneret. spg = spinning-glands. ig = thoracic ganglion. tr = trachea. pedipalps of the females are leglike structures usually with a terminal unguis, but in the male are more or less swollen to serve as accessory organs in copulation. The four pairs of seven-jointed legs are all similar in structure and serve for walking, differing in relative length in different genera. In the embryo the abdomen is distinctly segmented and bears five or six pairs of rudimentary appendages, the more ante- rior of which later disappear, while the two or three posterior pairs persist as the spinnerets (sp), so called from the occur- rence on them of the openings of the ducts of the spinning- glands (spg). These are very numerous and open at the apices of the spinnerets, each gland producing a fluid secretion which quickly hardens on exposure to the air to form a silken. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original wo
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
