460 AMERICAN Sl'IDEKS AND THEIR SI'INNINGWOKK. 



sign of a pedicle, but tliis may bo due to poor preservation; and a single 

 one not only has no pedicle, but appears to be formed of a lighter, flim- 

 sier tissue, and may belong to a different species. 



The egg cocoon of a spider of exactly the same size, shape, and gen- 

 eral appearance as those described above, excepting that from a break in 

 the stone there is no trace of a pedicle, was found by Scudder in the shales 

 at Green River, Wyoming. A single specimen was also found at Floris- 

 sant, Colorado, having the same general appearance, but with no trace of 

 a pedicle and slightly larger than any of the others, being six millimetres 

 long 'and four millimetres broad. It is, of course, impossible to say that 

 it is the same species. Still another was brought by the Princeton ex- 

 pedition from Florissant, different in the opposite direction, being con- 

 siderably smaller and so preserved as to appear broader than long. It is 

 provided with a pedicle one and four-tenths millimetres long, but is itself 

 only two millimetres long and two and a half broad. 



If the reader will turn back to pages 114 and 115, in the chapter on 

 General Cocooning Habits, he will see examples of cocoons which correspond, 

 both in size and general character, to these fossil cocoons of the 

 o em fpertiary. Cocoons of Ero thoracica, for example (Figs. Ill and 

 116), are represented in my drawings about twice natural size; 

 that is, they are about one-eighth inch long, or a little over three milli- 

 metres. They are suspended by a thread, from various objects, in a man- 

 ner which is suggested by the character of Aranea Columbia;. 



Another cocoon represented among these drawings (Figs. 112, 113) I 

 there attribute to Theridium frondeum on the authority of Dr. Marx. A 

 number of observations made since those pages were printed, both by my- 

 self and my secretary, have led me seriously to doubt the identification, 

 and to believe that this little orange colored hanging cocoon, which has 

 so long puzzled me to identify, is probably the cocoon of Theridiosoma 

 radiosum. We have found it a immber of times hanging close by the 

 snares of females of that species in Belmont Glen and other ravines of 

 Fairmount Park, and in the country surrounding Philadelphia; and no 

 other species was found in the neighborhood to which such a cocoon 

 could be attributed. I am therefore inclined at the present date to be- 

 lieve that the Eay spider is responsible for this pretty little egg sac. In 

 addition to this, I have examined young specimens raised from the cocoon, 

 and although the determination of a species by just hatched spiderlings is 

 well known to be extremely uncertain, yet this examination has 

 Theridio- confirmed me in the above opinion. The shape of cephalo- 

 Cocoon thorax and abdomen, arrangement of eyes, proportion of legs, 

 and general ensemble of the younglings lead me to conclude 

 that, if they are not Theridiosoma, they belong to no species with which 

 I am acquainted. 



In further confirmation I may add that Dr. L. Koch says of the cocoon 



