Text-book of comparative anatomy . he following extremities (2-7) are inner-vated from the ganglia of the ventral chord, 2 and 3 from the mostanterior ganglion, which consists in the larva of two separate ganglia. PANTOPOIA 423 The 2d pair of extremities is generally shorter than those which follow,and in several genera is wanting. The 3d pair of extremities isdeveloped in the males of all Pantopoda, and functions in them asegg-carriers. In several genera it is wanting in the females. Theextremities 4-7 are never absent, they consist of nine joints, andend in claws, and are in comparison with
Text-book of comparative anatomy . he following extremities (2-7) are inner-vated from the ganglia of the ventral chord, 2 and 3 from the mostanterior ganglion, which consists in the larva of two separate ganglia. PANTOPOIA 423 The 2d pair of extremities is generally shorter than those which follow,and in several genera is wanting. The 3d pair of extremities isdeveloped in the males of all Pantopoda, and functions in them asegg-carriers. In several genera it is wanting in the females. Theextremities 4-7 are never absent, they consist of nine joints, andend in claws, and are in comparison with the body exceedinglylong, giving the animal a spider-like appearance. All the extremitiesare uniramose. The nervous system in the adult animal consists of a supra-cesophageal ganglion, an cesophageal commissure, and a ventral latter has 4 or 5 pairs of ganglia, from which arise the nervesfor extremities 2 - 7 : it ends posteriorly with one or two pairs ofreduced ganglia, the last of which gives off nerves to the FIG. 2SS.—Nymphon hispidum, male, ventral side (after Hoek). The set;e are , Limbs ; (1, chelicerse ; 3, egg-carriers); s, proboscis ; a?j, abdomen. Since the most anterior ganglion of the ventral chord consists of2 or 3 pairs of ganglia, distinct in the larva, the complete numberof the pairs of ganglia in the ventral chord is 8, 7 of whichbelong to the trunk and 1 to the abdomen. According to this thenumber of trunk segments and also of pairs of limbs must originallyhave been 8. From the supra-cesophageal ganglion the nerves for theeyes arise, and also those for the first pair of limbs and some of thosefor the proboscis. Some of the other proboscis nerves have their rootsin the anterior portion of the first ventral ganglion. The nervoussystem of the proboscis with its ganglion is very complicated. Four eyes, each with a cuticular lens and a retina surrounded bypigment, lie on a prominence on the dorsal side of the first trunksegment. Th
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
