NOTES ON MIRANDA AURANTIA 1 45 



pyriform or pear-shaped glands are present in large numbers. Their 

 function is the production of silk for the attachment disks. The 

 ampullae glands produce the silk for the formation of "drag-lines" 

 in the net. These are not numerous. Cylindical glands are present 

 in small numbers. They produce the silk from which the egg-bag 

 is made. There are two poison glands that discharge their contents 

 through a long slender duct that opens near the tip of the claw ol 

 the chelicera. Glands that are lacking in Aurantia are: aggregate, 

 lobed and cribellum glands. 



The eggs of M. Aurantia are laid in a mass protected by two 

 layers of silk and enveloped in a waterproof bag. Most of these 

 egg-sacs are attached to thistles or milkweed or golden rod. Bu 

 many were found attached to such objects as cast-off window 

 screens, pieces of timber projecting from lumber piles, discarded 

 fence-posts, and some were fastened under the eaves of an old barn. 

 The egg-sac is about the size of a hickory nut — the average diameter 

 of observed specimens was about 22mm. The size was constant 

 in a very large majority of cases. But some egg-sacs measured 

 30 mm. and a few only 15, or even 12 mm. in diameter. The 

 average egg-sac contains about a thousand eggs. But some have 

 only a little more than five hundred, and a few were found that 

 contained about eight hundred. The reason for this is not clear 

 from observation, and there is none given in the literature of the 

 subject as far as it has come under my notice. A difference of 

 twenty or fifty could easily be traced to individual peculiarities. 

 But a difference ranging from two to five hundred in the same 

 species seems to need a more substantial explanation than individual 

 peculiarity or fertility. 



The eggs hatch in a short time — about two weeks for specimens 

 observed in this locality. But the spiderlings remain in the egg-sac 

 until the following spring. While still enclosed in the sac, they 

 develop those canabalistic tendencies that are remarkable in the 

 adult. An egg-sac of this species opened on September 17, 1916, 

 contained 101S live spiderlings, and about 200 remains of their 

 weaker companions that had succumbed to the canabalism of the 

 stronger spiders. 



It is certain that M. Aurantia sheds its outer layer of the 

 cuticula. I have found the molts from time to time, but have been 

 unable to determine thus far, how often this happens. Exact 

 observations on this point do not seem to have been made, or if 



