. Beginners' Zoology . to its mouth (Figs. 85, 86.) They are in form and in use-more like fingers than feet. In front of the foot jaws are two pairs of thin jaws(maxilla;) and infront of the thinjaws are a pair ofstout jaws (mandi-bles) (Fig. 8s). Dothe jaws movesidewise or upand down. Whichof the jaws has ajointed finger (palp) attached to it? Do all the appen-dages for taking food have both exopod and endopodbranches on a basal Stalk or protopod. Which of theappendages have a scalloped * How would you knowfrom looking at the crayfish that it is not merely Why are there no
. Beginners' Zoology . to its mouth (Figs. 85, 86.) They are in form and in use-more like fingers than feet. In front of the foot jaws are two pairs of thin jaws(maxilla;) and infront of the thinjaws are a pair ofstout jaws (mandi-bles) (Fig. 8s). Dothe jaws movesidewise or upand down. Whichof the jaws has ajointed finger (palp) attached to it? Do all the appen-dages for taking food have both exopod and endopodbranches on a basal Stalk or protopod. Which of theappendages have a scalloped * How would you knowfrom looking at the crayfish that it is not merely Why are there no pincers on the hind feet ? Sense Organs. — Find the antenncc, or long feelers (, 90). Are the antennae attached above or below the Fig. 87. ?Gill cover removed and gills , gill — Lengthwise Section of Male Crayfish c, heart; yjr, artery to head; ^<i, artery to abdomen; A?«, stomach; 27, intestine;L, liver; T, spermary; Go, opening of sperm duct; G, brain; N, nerve chain. Find the pair of antenmtles, or small feelers. Are theirdivisions like or unlike each other. Compare the lengthof the antennules and the antennae. Compare the flex-ibihty of the antennae with that of the other appendages. CRUSTACEANS 57 Observe the position of the eyes (Figs. 81, 88). How longare the eyestalks . Is the stalk flexible or stiff i Touch theeye. Where is the joint which enables the stalk to the outer covering of the eye hard or soft. A mountedpreparation of the transparent covering (cornea) of theeye, seen with lower power of microscope, reveals that thecornea is made up of many divisions, called facets. Eachfacet is the front of a very small eye, hundreds of whichmake up the whole eye, which is therefore called a com-pound eye. The elongated openings to the car s
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