326 ARACHNIDA—ARANEAE CHAP. 
spinning glands open. These are often very numerous, especially 
in the orb-weaving spiders, where the spinning powers are most 
highly developed. They consist of two portions, a cylindrical or 
conical basal part, succeeded by a very fine, generally tapering 
tube. 
In some spiders the fusulae are all much alike, but usually a 
few very much larger than the rest are noticeable under the 
microscope, and these are often alluded to as “spigots.” The 
smaller ones are also divisible into two kinds, a few short conical 
fusulae being noticeable amongst the much more numerous 
cylindrical tubes. We shall treat of the functions of the various 
fusulae later (see pp. 335 and 349). 
Simon remarks that though the battery of fusulae is most 
complicated in those spiders which possess the greatest spinning 
powers, it 1s by no means among them that extremely long 
spinnerets are developed. The posterior spinnerets of some of the 
Hersiliidae are of great length, but these spiders spin very little 
except in forming their egg-cocoons. 
In addition to the six spinnerets, and just in front of them, 
there is to be found in some spiders an extra spinning organ in 
B es the form of a 
SSS = —— double sieve-like 
a__ = = K\\ plate, the “ cri- 
bellum.” — This 
: is always corre- 
ie ee j lated with a 
comb of curved 
bristles on the 
metatarsi of the 
fourth pair of 
h( os — legs, the “cala- 
Pt a yee mistrum.” Such 
importance is 
i. oe are. Ss ] zi >) T } , } ] } 7 
Fic oe: A, Spinnerets of Amaurobius sunilis P. Much agsioned to these 
enlarged. a, Anus; cr, cribellum; 7.s, inferior spinneret ; S = 
m.s, median spinneret ; s.s, superior spinneret. B, Part of Organs by Simon, 
the 4th leg of the same Spider, showing the calamistrum (ca) ne ; 
on the metatarsus. that the Araneae 
FE 
SANA T Ns 
Wpret 
Veraeare divided 
by him according to whether they are present or absent, 
into CRIBELLATAE and KCRIBELLATAE. This is probably an 
exaggerated view of the importance of these organs, and the 
