. Ragni americani e il loro lavoro di filatura. Una storia naturale dell'orbweaving ragni degli Stati Uniti, con speciale riguardo alla loro industria e abitudini. Ragni. che Loro swing bozzoli libera, come Argiope e Theridium; vale a dire che la crociera si blocca con la schiena verso il basso mentre ovipositing. Ma in molti casi di femmine che liave rivestite per me in scatole, le uova devono essere state poste in posizione di retromarcia, poiché il bozzolo è stata fissata al fondo della scatola. Naturalmente, le specie che fissano i loro bozzoli di varie superfici, come fanno molti Epeiras e più Tubeweavers, depositare il

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. 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. who swing their cocoons free, as Argiope and Theridium; that is to say, the spider hangs with her back downward while ovipositing. But in many cases of females that liave cocooned for me in boxes, the eggs must have been placed in the reverse position, since the cocoon was attached to the bottom of the box. Of course, the species that fasten their cocoons to various surfaces, as do many Epeiras and most Tubeweavers, deposit the eggs downwards. Other fixed cocoons have as ^lo. 237. Epeira strix placing eggs into a . „ , , , , , , „ flossy boll of silk. (After Emerton.) manirestly been placed upwards, as, tor ex- ample, those spun on the under surface of stones, fallen logs, etc. Others, again, have been laid while the spider was in a vertical position, as when cocooning upon loose bark of trees and similar vertical sites. The bodily attitude appears to make little or no difference as to the facility with which the female can deposit her eggs. Whether directing them upward (with the dorsum towards the earth), or directing them downward (with the dorsum towards the sky), or depositing them against a vertical surface, with the head downward or upward, as the case may be, the mother is able to empty the ovaries with equal comfort and ease. Mr. Emerton has observed several species in the act of ovipositing, and his brief notes upon the manner thereof are as follows i^ Epeira strix first spins a rounded bunch of loose threads, into the middle of which ... she discharges her eggs, as shown in Fig. 237. The eggs, which are little drops of jelly, are held up by the loose threads until the spider has time to spin for them a covering of strong silk. It is to be regretted that the description here is so indefinite, as the term "cov- ering of strong silk" may imply either the flossy boll which is inva

Parole chiave associate all'immagine

• bookcentury1800
• bookdecade1880
• booksubjectspiders
• bookyear1889