. 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. 48 AMERICAN SPIDERS AND THEIR Fia. 43. Anterior spinneret of Epeira diadeniata. (After Un- derbill.) ss, spinning spools; sp, spigot; , pyriform glands with their ducts, The glandular epithelium is repre- sented, , ducts belonging to the spigots; sp, 'probably of cylindrical glands, Spools Vary. cylindrical gland, the only larger gland which dis- charges here. On the inside of this horny cone
. 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. 48 AMERICAN SPIDERS AND THEIR Fia. 43. Anterior spinneret of Epeira diadeniata. (After Un- derbill.) ss, spinning spools; sp, spigot; , pyriform glands with their ducts, The glandular epithelium is repre- sented, , ducts belonging to the spigots; sp, 'probably of cylindrical glands, Spools Vary. cylindrical gland, the only larger gland which dis- charges here. On the inside of this horny cone is attaclied a long yellowish cord or point, upon whicli strong nuiscles are inserted in order to move the cone against tlie spinneret. Mr. Undcrhill figures the spigots or large spin- ning tubes which issue upon the posterior and anterior spinnerets. ^ The former are situated upon the interior margins and are connected with two very large glands which are doubtless the cylin- drical glands as heretofore described. These spig- ots are shown at Fig. 43 together with a portion of the ducts leading to their appropriate glands (not represented) which lie below the pyriform glands. Fig. 44 shows one of these anterior spig- ots, , compared with two spools ss. of the same spinneret. Mr. Blackwall announced the fact for the first time, so far as I know, that the spools vary greatly in number in different species, and also differ considerably in size not only in individuals of the same species, but often even on the same spinnerets. The larger species of the Epeiroids have the spinnerets most amply provided with spools, and Blackwall ex- presses the opinion that the total number does not greatly exceed a thou- sand, even in adult females of Epeira quadrata, whose weight is about twenty grains, and in many other species it is smaller. As illustrating the difference in various genera it may be stated that Tegenaria domestica and Tegenaria civilis, for ex- amjile, have less than four h
Size: 1109px × 2253px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectspiders, bookyear1889
