Outlines of zoology . .—Dorsal surface oiAptiscancriformis. ?— From BronnsThierreich. In the anterior region are the two com-pound eyes, and behind them thesimple unpaired eye. The whip-likeoutgrowths of the first thoracic ap-pendage project laterally. f- Antenna. Pre-oral. V Second antenna. (This is sometimes absent, andapparently always in certain species.) 3- Mandible. Oral. - A- Maxilla. l5- Maxillipede. 300 PHYLUM ARTHROPODA. f6. First thoracic foot (leg-like).Thoracic J 7-16. Other ten thoracic feet (swimmers). (Pregenital). j The i6th in the female carries an egg-sac or brood- t chamber
Outlines of zoology . .—Dorsal surface oiAptiscancriformis. ?— From BronnsThierreich. In the anterior region are the two com-pound eyes, and behind them thesimple unpaired eye. The whip-likeoutgrowths of the first thoracic ap-pendage project laterally. f- Antenna. Pre-oral. V Second antenna. (This is sometimes absent, andapparently always in certain species.) 3- Mandible. Oral. - A- Maxilla. l5- Maxillipede. 300 PHYLUM ARTHROPODA. f6. First thoracic foot (leg-like).Thoracic J 7-16. Other ten thoracic feet (swimmers). (Pregenital). j The i6th in the female carries an egg-sac or brood- t chamber. There are eleven thoracic rings on the /17-68. Fifty-two abdominal feet, to which there corre-i Post-genital). \ spond only seventeen rings on the body. The large dorsal shield is not attached to the segments behind theone bearing the maxillipedes. Many of the thin limbs doubtlessfunction as gills. The genital apertures are on the sixteenthappendages. The anus is on the last segment of the Fig. 154.—Daphnia. £.t Eye ; Afi, second antenna ; , first antenna ; ., spine;/.fiirca; j., setae; /4((.,rudimentaryabdomen ;t.^ caudal fork ; g^.^ gut; /-j, thoracic limbs. There is a pair of ventral ganglia to each pair of limbs ; the ventralnerve-cords are widely apart; and the cephalic ganglion isremarkably isolated. There is periodic parthenogenesis. ENTOMOSTRA CA. 301 {b) Cladocera. Small laterally compressed water-fleas, with fewand somewhat indistinct segments. The shell is usually bivalved,and the head often projects freely from it. The second antennseare large, two-branched, swimming appendages, and there are4-6 pairs of other swimming organs. The heart is a little sacwith one pair of openings. An excretory organ (the shell ormaxillary gland) opens in the region of the second maxilte. Itis the Entomostracan equivalent of the antennary green glandof Malacos
Size: 1318px × 1895px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
