Beginners' zoology . A Snail. Study of a LiveSnail or Slug. — Is ?> -I 2, mouth; vf, hf, feelers; e, opening of egg duct; /, foot; moist ? Do land >««, mantle; /?<, opening to lung; a, vent. snails and slugs have lungs or gills? Why? How many pairsof tentacles have they? What is their relative length and position?The eyes are dark spots at bases of tentacles of snail and at thetips of the rear tentacles of slug. Touch the tentacles. Whathappens? Do the tentacles simply stretch, or do they turn inside io6 BEGINNERS ZOOLOGY. ?j ^^P^^^ P^ JJI H ^Hkv«bJr>i«»<<« R ^?-^ \^ Uf^^ i^^
Beginners' zoology . A Snail. Study of a LiveSnail or Slug. — Is ?> -I 2, mouth; vf, hf, feelers; e, opening of egg duct; /, foot; moist ? Do land >««, mantle; /?<, opening to lung; a, vent. snails and slugs have lungs or gills? Why? How many pairsof tentacles have they? What is their relative length and position?The eyes are dark spots at bases of tentacles of snail and at thetips of the rear tentacles of slug. Touch the tentacles. Whathappens? Do the tentacles simply stretch, or do they turn inside io6 BEGINNERS ZOOLOGY. ?j ^^P^^^ P^ JJI H ^Hkv«bJr>i«»<<« R ^?-^ \^ Uf^^ i^^ ,i^ Ji ^^^^^^ HB^tartitf HHI^^HHBHI Hl^^^l H^IIh out as they are extended? Is the respiratory opening on the right or the left side of the body? On the mantle fold or on the body? (Figs. 202-3-4.) How often does the aperture open and close ? Place the snail in aFig. 203. — A Slug. ^ ^ , , _^ moist tumbler. Does the whole under surface seem to be used in creeping? Does thecreeping surface change shape as the snail creeps ? Do any foldsor wrinkles seem tomove either toward thefront or the rear of itsbody? Is enough mu-cus left to mark thepath travelled? Thefold moves to the front,adheres, and smoothsout as the slug or snailis pulled forward. Cephalopods. The ^i^- 204-—Circulation and Respiration highest and best de- ^^ ^^?^^- , J ,, a, mouth; ^, ^, foot; f. vent: rf, rf, lung; A, heart. Veloped molluscs are Blood vessels are black. (Perrier.) the cephalopods, or head-footed molluscs. Surrounding themo
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
