Beginners' zoology . Which of theappendages have a scalloped edge. How would you knowfrom looking at the crayfish that it is not merely ascavenger. Why are there no pincers on the hind feet ? Sense Organs. — Find the aiitemicB, or long feelers (, 90). Are the antennae attached above or below theeyes ? (Fig. 87.) Fig. 87. — Gill cover removed and gills , gill Fig. 88. — Lengthwise Section of Male Crawfish. f, heart; v4c, artery to head; yja, artery to abdomen; /iTwi, stomach; Z>, intestine;Z, liver; 7, spermary; Gt;, opening of sperm duct; (7, brain; iV^, nerve chai
Beginners' zoology . Which of theappendages have a scalloped edge. How would you knowfrom looking at the crayfish that it is not merely ascavenger. Why are there no pincers on the hind feet ? Sense Organs. — Find the aiitemicB, or long feelers (, 90). Are the antennae attached above or below theeyes ? (Fig. 87.) Fig. 87. — Gill cover removed and gills , gill Fig. 88. — Lengthwise Section of Male Crawfish. f, heart; v4c, artery to head; yja, artery to abdomen; /iTwi, stomach; Z>, intestine;Z, liver; 7, spermary; Gt;, opening of sperm duct; (7, brain; iV^, nerve chain. Find the pair of antenmilcs, or small feelers. Are theirdivisions hke or unlike each Compare the lengthof the antennules and the antennae. Compare the flex-ibility of the antennae with that of the other appendages. CRUSTACEANS 57 Observe the position of the eyes (Figs. 8i, 88). How longare the eyestalks . Is the stalk flexible or stiff} Touch theeye. Where is the joint which enables the stalk to move}Is the outer covering of the eye hard or 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 openin
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
