238 Mr. J. Blackwall on the Structure y Functions 



vision for the development of the young in the foetal state by an en- 

 larged capacity in the cocoons consequent on the margins of the 

 compact parts becoming detached by the expansive force within, the 

 eventual liberation of the young being effected by the rupture of the 

 zone. 



Theridion callens fabricates a very remarkable balloon-shaped co- 

 coon about one-eighth of an inch in diameter. It is composed of 

 soft silk of a loose texture and pale brown colour, inclosed in an 

 irregular network of coarse, dark red-brown silk ; several of the lines 

 composing this network unite near the lower and smaller extremity 

 of the cocoon, leaving intervals there through which the young pass 

 when they quit it, and, being cemented together throughout the re- 

 mainder of their extent, form a slender stem, varying from one-tenth 

 to half of an inch in length, by which the cocoon is attached to the 

 surface of stones and fragments of rock, resembling in its figure and 

 erect position some of the minute plants belonging to the class Cryp- 

 togamia. The eggs are large, considering the small size of the spider, 

 five or six in number, spherical, not agglutinated together, and of a 

 brown colour*. 



An elegant vase-shaped cocoon, composed of white silk of a fine 

 compact texture, and attached by a short foot-stalk to rushes, the 

 stems of grass, heath, and gorse, is constructed by Agelena brunnea ; 

 it measures about one-fourth of an inch in diameter, and contains 

 from forty to fifty yellowish-white, spherical eggs enveloped in white 

 silk connected with the interior of the cocoon contiguous to the 

 foot-stalk. Greatly to the disadvantage of its appearance, the entire 

 cocoon is smeared with moist soil, which drying serves to protect it 

 from the weather, and as an additional security, the extremity is 

 closed and directed downwards. 



Theridion riparium fabricates a slender, conical tube of silk of a 

 very slight texture, measuring from one and a half to two and a 

 half inches in length, and about half an inch in diameter at its lower 

 extremity. It is closed above, open below, thickly covered externally 

 with bits of indurated earth, small stones, and withered leaves and 

 flowers, which are incorporated with it, and is suspended perpendi- 

 cularly, by lines attached to its sides and apex, in the irregular snare 

 constructed by this species. In the upper part of this singular do- 

 micile the female spins several globular cocoons of yellowish-white 

 silk of a slight texture, whose mean diameter is about one-eighth of 

 an inch, in each of which she deposits from twenty to sixty small 

 spherical eggs of a pale yellowish-white colour, not agglutinated 

 together. The young remain with the mother for a long period after 

 quitting the cocoons, and are provided by her with food, which con- 

 sists chiefly of antsf. 



Oonops pulcher constructs several contiguous, subglobose cocoons 

 of white silk of a fine but compact texture in the crevices of rocks 

 and walls, and among lichens growing on the trunks of trees ; each 



* Transactions of the Linnaean Society, vol. xviii. p. 629, 

 f Researches in Zoology, p. 356. 



