Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . upying a largeportion of the body, and is divided by numerous constrictions intoirregularly disposed ca3ca ; their walls are provided with hepaticcells. Near the mouth are two large lobulated 163glands, that seem to be salivary. No traces ofrespiratory organs have yet been found; and therespiration in Macrohiotus^ as in Demodex,must be cutaneous. In some of the small and parasitic trachearyArachnids or mites, certain pairs of legs areterminated by adhesive suckers, and
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . upying a largeportion of the body, and is divided by numerous constrictions intoirregularly disposed ca3ca ; their walls are provided with hepaticcells. Near the mouth are two large lobulated 163glands, that seem to be salivary. No traces ofrespiratory organs have yet been found; and therespiration in Macrohiotus^ as in Demodex,must be cutaneous. In some of the small and parasitic trachearyArachnids or mites, certain pairs of legs areterminated by adhesive suckers, and others areoccasionally terminated by setae, as in the itch-mite {Sarcoptes Galei^Jig. 163.). The mouth, in all Arachnids, is situated onthe anterior segment, and is provided with in-struments adapted either for suction or masti- sarcoptes Gaiei, or itch- ,. T ^1- -x* L ^1 -y , o insect, magnified. cation. In the parasitic mites the rudiments of the jaws are more or less enveloped in a sheath formed by the lower lip: the maxillary palpi are usually the only parts which have free * CCLXXXII. t CCLXXXIII. X XLIII. § ARACHNIDA. 447 and independent movements, and their extremity is commonly armedeither with a hook or with a pair of small nippers. In spiders the parts called mandibles {^fig. 172, cl) are situated atthe front of the head and are terminated by a moveable and verysharp hook, which is pierced at its extremity by a small fissure,serving to give issue to the poison secreted by a gland lodged in thepreceding joint. The maxillse (ib. h, h) are two in number, and thelabium (ib. e) situated between these organs is composed of asingle piece. The maxillary palpi (ib. c), compared with those ofinsects, are of great length and size, and resemble the thoracic feet,which, in the Mygale, they nearly equal in length. In female spidersthey are terminated by a single moveable claw: in the males the lastjoint (ib. d) is dilated, and presents a more complicated the sc
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1850
