File:Image from page 100 of "Introduction to zoology; a guide to the study of animals, for the use of secondary schools;" (1900) (14784978145).jpg

Identifier: introductiontozo00dave Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company London, Macmillian and co., ltd. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: cond pair of slits; these spiders have four lung sacs(hence Tetrapne union es).2 The best known of our spiders are the orb web-spinninggarden spiders, belonging chiefly to the genera Epiera3or Argiope 4 and the house cobweb spinning spiderTheridium.5 Argiope spins webs of very geometric form betweenstems of weeds, Branches of shrubs, or along fences inour meadows.6 Its web belongs to the full-orb type in fa, spider. 2 A key to the seven subdivisions of the Araneina will be found at theend of this Chapter, page 95. 3 e/uLireipos, skilful, experienced. 4 Name of a nymph. ° eypidiov, a little wild animal. 6 Fig. 78. 80 THE SPIDER AND ITS ALLIES 81 contrast to the condition in other orb-spinners, in whicha sector of the circle is omitted or in which a sector onlyis formed. At the centre of the web of Argiope there isan oval, closely woven shield of silk. The spider, when atrest, is usually found upon or under this shield. Anotherfrequent character of the web is a zigzag ribbon, extending

Text Appearing After Image: FIG. 78. — Web of Argiope, placed horizontally over a fish-way. by W. H. C. P. Photo. downward from the central shield, and sometimes upwardalso, and attached to two or more radii. This zigzag,which is doubtless the winding1 stair referred to in O the rhyme, The Spider and the Fly, is formed, as Fig.79 shows, by preventing the fusion of the strands as theyemerge from the spinnerets. G 82 ZOOLOGY The genus Theridium and its allied genera constitute themost extensive family found in the United States. Thespiders belonging to the family are small, with relativelylarge, rounded abdomens. They have eight eyes, arrangedin the manner shown in the diagram, Fig. 80. Their webs show no attempt atgeometric arrangement,such as is seen in theweb of Argiope andother orb-weavers, butthe threads cross inevery direction, forminga sort of intricate trestle-work. The speciesTheridium tepidarioniuiis the common littlecobweb-spinner of ourhouses and barns ; it alsospins about fences. Itscolor varies fro

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