LIMs'lCAN SOCIETY OF LO>i)OX.. 79 



by .spiders in the forniatioii of the jjrotective covering of their 

 egg.s. Tlie strands were arranged in circular sweeps po cha- 

 racteristic of the filk found in the egg-sncs of spiders. 



4. A slide obtaitied from the egg-sac of the house-spider at a 

 magnification of lUO diameters indicates the circular sweep of the 

 silk fibres and serves to illustrate my remarks. 



i'roin the appearances presented I was led to the conclusion 

 that I had the product of a spider to deal with. 



5. In addition the contents of the sac consisted of the usual type 

 of silk we find surrounding the eggs and the remains of empty 

 egg-shells and dried-up spiders. 



I could find no reference to any spider egg-sac at all like it. 



Messrs. E. I. Pocock and llichard Hancock wei'e unable to 

 identify it. I met with the same experience at the Natural 

 History Museum, but on carefully looking througli the cabinet of 

 spider egg-sacs there I found a single identical egg-sac which 

 showed a precisely similar puncture to tliose shown in my spe- 

 cimen. It wH,s unnamed, and I could learu nothing about where 

 it was found. 



J was referred by the authorities of the Museum to Monsieur 

 Eugene Simon of Paris, who, on April 10, 1919, wrote me as 

 follows : — "It is perhaps the egg-sac of Gyrtaraclme hihvrcnlifera 

 (E. S.). The egg-sac of this is unknown, and the supposition is 

 formed on analogy with that of the tropical species of the same 

 genus.*' 



Simon's description of this Ai'giopod states tli;it it is found in 

 Africa, Asia, Japan, Malaya, and on the shores of the Western 

 Mediterranean. 



6. It may be of interest if I call attention to one or two poinds 

 suggested by my first slide. 



VV^e have the egg-sacs of Ci/rtarachne tahercMlifera. To the 

 left of these possibly the egg-sac of Zoropsis spinimaniis (Dufour). 

 Below we have the outer and inner envelope of the egg-sac of 

 Drassodes hijpocritica, and to the left of these the cocoon of the 

 nym.phal stage of some Lepidopterous insei-t. The cocoon has 

 been formed by the incurving of a leaf (Arhictus'?), surrounded by 

 strands of brown Lepidopterous silk. I show a slide of this silk 

 so markedly different from the silk employed in the construction 

 of the egg-sa^'S of spiders. The trellis-like arrangement of the 

 strands are a point of distinction. (See figui'e B on page .SO.) 



7. This feature is shown in the silk of the cocoon of perluips 

 one of the best-known examples, that of the silkworm Bomhyx 

 iiiori. My photomicrograph of this at a magnification of oO 

 diameters has been obtained by direct and -not transmitted light. 



