. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . Fig. 19.—Arenicola, from the right: g, gills; Id, dorsal setae; v, ventral setae; e, excretory openings; Ih, head folds; p, papillae on the protruded pharynx. After Ash worth. The number of forms concealed in the sand is astonishingly great. Many sea anemones build tubes in the sand in which they can with- draw completely. Turbellarian and nemertine worms conceal them- selves in the sand from which they may be lured to the surface by

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Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology