. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ARACHNID A. 467 developed system of muscle-bands. There are no special organs either for respiration or circulation. The mouth (Fig. 214, m), surrounded by papilla, lies at the anterior extremity of the body, and leads into a tubular mouth-cavity containing, imbedded in its walls, a pair of chitinous or partly calcareous teeth, and receiving the ducts of two glands {sg) which have been regarded as salivary or perhaps poisonous in function. Behind, this cavity opens
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ARACHNID A. 467 developed system of muscle-bands. There are no special organs either for respiration or circulation. The mouth (Fig. 214, m), surrounded by papilla, lies at the anterior extremity of the body, and leads into a tubular mouth-cavity containing, imbedded in its walls, a pair of chitinous or partly calcareous teeth, and receiving the ducts of two glands {sg) which have been regarded as salivary or perhaps poisonous in function. Behind, this cavity opens into a muscular pharynx which is connected by a short a3so- phagus with the mid-gut (s). At the junction of this with the rectum or hind-gut is a pair of cfiecal diverticula {mg\ possibly Malpighian tubules, and into the hind-gut there also open the ducts of the reproductive organs, the hind-gut thus serving as a cloaca. It opens on the ventral surface of the body a short distance from the pos- terior extremity and therefore in front of the last pair of appendages. The nervous system consists of a supracfisophageal ganglion (ce) united with a chain of four pairs of ventral ganglia. No special sense-organs occur except two eyes situated at the sides of the head. The sexes are distinct, the reproductive organ being un- paired and opening into the cloaca, into which opens also in both sexes au unpaired accessory gland. The Tardigrada occur in water usually, especially in such locations as the gutters on the roofs of houses, though some- txines found also among moss. The group contains but a small number of genera, of which Macrohiotus is perhaps the most Fig. 214. — Diagram op Stkucture op Macrobiotua megalonyx (after von Erlan- oek). an — iiuus. ce = cerebral gauglion. e^— e* =: appendages. h = bindgut. m = moutb. mg = mid-gut diverticula. oc = eyv. a = midgut. iff = salivary (?) glands. so = suboesopbageal gan- Please note that these images are extracted
Size: 1163px × 2149px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1896
