Text-book of comparative anatomy . character may,however, be more or less indistinct, or may even be lost as the limbsdevelop into the corresponding limbs of the adult, In attempting a comparative review of the limbs throughout theclass of the Crustacea, only the most important points can be touchedupon. The setae with which they are often provided, and whose formand arrangement are extremely important for classification, cannothere be taken into consideration. 1. The Limbs of the Head. In all the Crustacea the head carries 5 pairs of limbs, which arecalled, folloAving the order from before ba
Text-book of comparative anatomy . character may,however, be more or less indistinct, or may even be lost as the limbsdevelop into the corresponding limbs of the adult, In attempting a comparative review of the limbs throughout theclass of the Crustacea, only the most important points can be touchedupon. The setae with which they are often provided, and whose formand arrangement are extremely important for classification, cannothere be taken into consideration. 1. The Limbs of the Head. In all the Crustacea the head carries 5 pairs of limbs, which arecalled, folloAving the order from before backward, the anterior antenna?,posterior antennae, mandibles, anterior maxillae, and posterior 3 anterior pairs correspond with the 3 pairs of limbs of theNavplius. a. The Anterior Antennae (Antennules) (Fig. 209). These lie in front of the mouth, and consist typically of a singlerow of joints. As a rule they function as organs of touch, but usuallyalso carry the olfactory organs, and occasionally the auditory FIG. 209.—Anterior antennae (antennules) of various Crustaceans. A, Of Astacus (afterHuxley); o, auditory sac. B, Of Munnopsis typica, Isojiod aUaGeo/royi $(after Glaus), without the seta; pi, plate. D, Of Cyclops serrulatus 6 (after Glaus); rf, olfactoryhairs. E, Of Daphnia index (after Leydig); rf, olfactory hairs ; g, ganglion. Entomostraca.—In all Entomostraca the antennules consist typically of a singlerow of joints. In the Phyllopoda (Fig. 209, E) they are small, carry numerousolfactory hairs, and are called feelers or olfactory antenna;. In the Ostracoda () they are strongly developed and occasionally provided with olfactory hairs, butchiefly function as locomotory organs for crawling and swimming. The anteriorantennre of the are strongly developed as swimming feet in the free-swim-ming forms, and are longer than any of the other limbs (Fig. 194). They carryolfactory hairs, and serve in the males as organs for seizing and h
Size: 2112px × 1183px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
