. The biology of spiders. Spiders; Insects. DISTRIBUTION 189 never yet been found elsewhere in the whole world, not even under the apparently similar clumps which are plentiful in the immediate neighbourhood. The sudden disappearance of spiders from a haunt confirms what may perhaps be called the individuality of distribution. Many jumping-spiders, for example, are but fleeting inhabitants of their neighbourhood. It is possible to find ten or twelve individuals within an hour at a place where, a week later, a day's search may be quite unrewarded. Our belief is, then, that although some spiders
. The biology of spiders. Spiders; Insects. DISTRIBUTION 189 never yet been found elsewhere in the whole world, not even under the apparently similar clumps which are plentiful in the immediate neighbourhood. The sudden disappearance of spiders from a haunt confirms what may perhaps be called the individuality of distribution. Many jumping-spiders, for example, are but fleeting inhabitants of their neighbourhood. It is possible to find ten or twelve individuals within an hour at a place where, a week later, a day's search may be quite unrewarded. Our belief is, then, that although some spiders are ubiquitous, there are many others which react strongly to change in the physical environment. This must imply susceptibility of internal organisation and need not necessarily be expressed in marked external features. It is, therefore, possible to find, within the limits of a single genus, such striking differ- ences as that of the two Zillas con- sidered above. These two stand at extremes of the scale and it is only reasonable to look for instances where a gradation of habits occurs—show- ing us, perhaps, the steps by which the process has come about. It is very easy to find examples which illustrate this. Four species of the genus Tegenaria are common in Great Britain, occurring in the situations mentioned below :. Fig. 76.—Epeira pyra- midata. The abdomen is bright yellow with brown marks. 1. Tegenaria derhamii. Nearly always indoors. 2. Tegenaria parietina. Usually indoors, sometimes outside. 3. Tegenaria atrica. Sometimes indoors, very often outside. 4. Tegenaria silvestris. Nearly always outside. There are here, therefore, what may be described as. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Savory, Theodore Horace, 1896-. London : Sidgwick & Jackson
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecti, booksubjectspiders
