Text-book of comparative anatomy . ight be called the embryonic Phyllosoma stage, are passed through. Thecharacteristics of this latter stage are as follows : There are 2 pairs of , and 2 pairs of maxillre. The thoracic limbs have all begun to form, pairs of maxillipedes and 5 pairs of ambulatory limbs. The 2 most posterior(ambulatory limbs) are only present as minute buds. The 6 anterior are biramose,but the exopodites of the 2d and 3d pairs of maxillipedes are degenerated evenduring embryonic life. There are two stalked lateral eyes, and the median Naupliuseye. In the
Text-book of comparative anatomy . ight be called the embryonic Phyllosoma stage, are passed through. Thecharacteristics of this latter stage are as follows : There are 2 pairs of , and 2 pairs of maxillre. The thoracic limbs have all begun to form, pairs of maxillipedes and 5 pairs of ambulatory limbs. The 2 most posterior(ambulatory limbs) are only present as minute buds. The 6 anterior are biramose,but the exopodites of the 2d and 3d pairs of maxillipedes are degenerated evenduring embryonic life. There are two stalked lateral eyes, and the median Naupliuseye. In the body 3 regions are to be distinguished. (1) Head with dorsal shield ;(2) thoracic region, in which the segmentation is indicated ; (3) a distinctly segmentedbut limbless abdominal region ending in a fork. Before the larva is hatched, however, in addition to the 2 posterior pairs ofambulatory feet which remained undeveloped, the 1st pair of maxillipedes dis-appear, and the 2d pair of maxillae and the 2d pair of antennae Fia. 20(3.—Phyllosoma of Palinurus (after Glaus), ad, Abdomen ; I, liver. In the larva hatched from the egg the above-mentioned regions of the body can berecognised—it is much flattened dorso-ventrally (like a leaf), and as transparent asglass ; it is called the younger Phyllosoma (Fig. 266). The older Phyllosoma larva is distinguished from the younger by the followingcharacteristics. The 1st pair of maxillipedes has formed anew, and the 2 posteriorpairs of ambulatory feet have developed. The 2 posterior maxillipedes again developexopodites, and on the ambulatory limbs the rudiments of the gills appear. Theabdomen is more elongated and shows the rudiments of the pleopoda. The larvathus already has, apart from its strange form, typical Decapodan transformation into the sexual form has not been observed. In the development of the Loricata we note :— 1. That during the processes which go on in the last part of embryoniclife the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
