STRUCTURE AND ECONOMY OF SPIDERS. 293 
as they are brought into contact with them. From 
this circumstance I was led to infer that the blue 
bands are fibrous, although their structure is so ex- 
ceedingly fine that I cannot detect it even with the 
assistance of the microscope, and that the imper- 
ceptible filaments of which they are composed adhere 
to objects, not in consequence of being glutinous, but 
solely by attaching themselves to inequalities on their 
surfaces. The following brief description of the 
manner in which the flocculi are fabricated, and of 
the curious apparatus employed in the process, gives 
additional weight to this opinion. 
There are on the metatarsi of the posterior legs of 
Ciniflo atrox two parallel rows of fine spines, mov- 
able at the will of the animal, which may readily be 
discerned by means of a lens having a magnifying- 
power of ten or twelve. They are situated upon a 
ridge on the abdominal side of the superior surface 
of the joint, commencing a little below its articulation 
with the tibia, and terminating at a strong spur near 
its extremity. The spines composing the upper row 
have a considerable degree of curvature, and taper 
gradually to a fine point, those of the lower row 
being stronger, more closely set, and less curved. 
This important appendage has received the name of 
calamistrum, and constitutes a striking character, which 
ought on no account to be omitted in descriptions of 
Ciniflo atrox. 
When the spider purposes to form a flocculus, it 
