BULLETIN 



OF THE 



ZltTSTITTJTIE. 



VOL. 9. SALEM, APR., MAY, JUNE, 1877. Nos. 4, 5, 6. 



REGULAR MEETING, MONDAY, MARCH 5, 1877. 

 MEETING this evening. The PRESIDENT in the chair. 

 Records read. 



Mr. JAMES H. EMERTON gave a very interesting com- 

 munication on cobwebs. He mentioned that : 



The only kinds of web made by all spiders are the egg 

 cocoons, which in their simplest form consist of two sau- 

 cer-shaped pieces fastened together at the edges. These 

 are not made of a single thread like those of caterpillars, 

 but of a great number of very fine threads drawn out at 

 once, so that the cocoon cannot be unwound. 



Like the cocoons are the bags which many spiders 

 make to protect themselves during the winter or while 

 moulting or laying eggs. - A bag of this kind is made by 

 the water spider, Argyronata, under water, attached to 

 plants. The air which remains among the hairs and spin- 

 nerets when the spider comes down from above the surface 

 collects in this bag, and finally fills it, so that the spider 

 lives as in a diving bell. 



ESSEX INST. BULLETIN. IX 5 (67) 



