18.01.2013 Views

The Descent of Man

The Descent of Man

The Descent of Man

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

tance <strong>of</strong> several feet or even yards (73. Wollaston,<br />

'On Certain Musical Curculionidae,' 'Annals<br />

and Mag. <strong>of</strong> Nat. Hist.' vol. vi. 1860, p. 14.),<br />

but it is not comparable with that made by the<br />

Orthoptera. <strong>The</strong> rasp generally consists <strong>of</strong> a<br />

narrow, slightly-raised surface, crossed by very<br />

fine, parallel ribs, sometimes so fine as to cause<br />

iridescent colours, and having a very elegant<br />

appearance under the microscope. In some cases,<br />

as with Typhoeus, minute, bristly or scalelike<br />

prominences, with which the whole surrounding<br />

surface is covered in approximately<br />

parallel lines, could be traced passing into the<br />

ribs <strong>of</strong> the rasp. <strong>The</strong> transition takes place by<br />

their becoming confluent and straight, and at<br />

the same time more prominent and smooth. A<br />

hard ridge on an adjoining part <strong>of</strong> the body<br />

serves as the scraper for the rasp, but this scraper<br />

in some cases has been specially modified<br />

for the purpose. It is rapidly moved across the<br />

rasp, or conversely the rasp across the scraper.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!