. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. Spiders. GENERAL CLASSIKICJATION AND STRUCTURK. 27. the translucent epiderm, rather than by pubescence. These colors are often very bright, shades of yellow and red prevailing, and bright metallic white or silver being frequent. The tough integument which covers the abdomen consists of three layers; the external one is a thin, transi)arent, horny membrane, nearly colorless, but more or less densely covered with colored hairs. Beneatli t
. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. Spiders. GENERAL CLASSIKICJATION AND STRUCTURK. 27. the translucent epiderm, rather than by pubescence. These colors are often very bright, shades of yellow and red prevailing, and bright metallic white or silver being frequent. The tough integument which covers the abdomen consists of three layers; the external one is a thin, transi)arent, horny membrane, nearly colorless, but more or less densely covered with colored hairs. Beneatli this lies the soft layer of pigmentary matter upon which the peculiar color of the body largely depends. The third or inner layer consists of an expanded network of muscular fibres, which are irregularly interlaced, and which must enable the spider forcibly to compress the abdomen. The muscles forming this layer are very faintly, if at all, marked with trans- verse striae. (Meade.) On the ventral side or venter near the base (anterior part) are situated two gills, breathing holes, or pulmonary sacs (bg). They are scales or plates symmetrically apposed on either side, form- ing the covering of cavities com- Pulmona- ⢠,⢠ii .1 . 1 â municatuig with the trachea) or air tubes. Externally they present the appearance of simple transverse slits in the venter. Each cavity contains about fifty extremely thin, triangular, white leaflets, fast- ' ="---^^^^§---'31"^^^^^^^ ened together at the edge of the breathing j,_ "^P hole. Each is double, being in fact a flat â ,â r,- <⢠1 .â r â â ' ^ Fig. 16. Diagram of location of spinning pouch with an opening on the lower side organs and their relations to other organs communicating with the outer air. The spi- ^:'Z^: ^:^^ZT^l racular plates are usually conspicuous objects , cylindrical glands; ep, epigynum; .1 , ,.~ . 1 11 n bgl, breathing gills; ac, alimentary canal; upon the venter, differing in color th
Size: 2459px × 1017px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectspiders, bookyear1889
