278 PROCEEDINGS OF THE ACADEMY OF [1883. 



spiderlings be hutched, she will, perhaps, drop down a foot or so, 

 if a first etfort to capture her he not successful ; but will not drop 

 to the ground, unless forced to do so. If guarding her eggs, she 

 must be forcibly separated from the cocoon. The young ones 

 take alarm sooner than their mother ; they drop down a few 

 inches — or, at times, two feet — every one on its tiny thread, 

 forming a pretty, swaying fringe. In a few moments, if all is 

 still, they climb up again ; but if frightened, will drop to the 

 ground, and run. The little ones in such case do not jump. 



It is a further interesting fact in so-called " mimicry " that of 

 several examples of P. aurora seen by Mr. Wright, one found on 

 a green bush was in color almost wholly green, with scarcelj' a 

 trace of red ; while two found on a hoar^'-white bush had simu- 

 lated the v/hite color of their habitat. The specimens, as described 

 above by Dr. McCook, approach in coloration the prevailing 

 hue of the Eriogonum on which they were nested, and he was 

 inclined to think that this is the normal color of the adult, which 

 is taken on as the animal matures; indeed, as the green and 

 whitish specimens were not sent to him, he would be inclined to 

 think (awaiting further evidence) that those colors ma}' have 

 been due to immature age. At least, the tendency to such colors 

 is strong in young spiders. However, the fact of mimicr^^ is not 

 improbable, as Dr. McCook had observed it in our native 

 Laterigrades. 



From the same gentleman and localit}^ Dr. McCook had 

 received a 9 specimen of Argiojje faKciata^y^hxiih is thus located 

 upon the Pacific Coast, giving this beautiful and interesting 

 spider a continental distribution. 



A Web-Spinning Neuropterovs Insect. — Dr. Henry C. McCook 

 announced that a small neuropterous insect, Psocus sexpunclatus, 

 had been lecently found on the Wissahickon Creek, Fairmount 

 Park, Philadelphia, by Mr. S. F. Aaron, of this Academy. This 

 is the first time, so far as the speaker was aware, that this insect 

 has been found in the United States, or indeed North America. 

 Mr. Aaron took the insects home in the paper boxes in which he 

 had collected tliem, and thus observed the fact which has hereto- 

 fore been noted of the p]uropean species, that thej^ spin ivebs. 

 McLachlan ' expresses the belief that both sexes possess the 

 power of spinning a web, which, he affirms, is not distinguish- 

 able fi'om that made by spiders. If a number of living speci- 

 mens be enclosed in a pill-box, it will be found that at the 

 end of a few hours the interior is traversed in all directions by 

 numerous lines of web. Mr. McLachlan further states that the 

 eggs, which are laid in clusters, are also protected with a web by 

 the female. These insects are very common in England, where 



' Monograpli of the Brit. Psotidse, Entom. Monthly Magz., vol. iii, 

 1866-G7, p. 228. 



