30 



AMKKICAN Sl'IDKltS AND THEIR SPINNINGWORK. 



sp.c 



sp.t 



Tlie spinning field, SF, is an elliptical slope, which is situated on the 

 inner side of the spinneret, and extends across the summit to the opposite 

 face of the tip. Tlie basal part of the spinneret is cylindrical 

 pP^J"^^"^^ and gradually grows smaller toward the spinning lield. At tlie 

 lower or inferior edge is a row of long, strong branclied bristles, 

 bb. On the inner surface, and at the border of the prolonged spinning 

 Held, is a group of much shorter, stifF, simple bristles, sb. 



On each posterior spinning field is placed a number of spools, which 

 may be estimated roundly at one hundred and twenty. Besides these, there 

 are five larger spools, sp, which after Bucholz and Landois we may dis- 

 tinguish as spigots. Through these spigots issue a corresponding number 



of cylindrical and treeform glands presently to 

 be described. That part of the spinning field 

 which runs downward toward the base is com- 

 posed of numerous rows of long, closely placed 

 spools, l.ss. ; while that part of the field on the 

 smumit is covered with short spools, s.ss. (See 

 Fig. 23.) Of the spinning spigots (Fig. 23), 

 four stand close together in one group towards 

 tlie middle of the spinning field, and one of 

 tliem is situated in the lower part of the field 

 (near l.ss.), and appears to be covered by the 

 long spinning spools. Of the four groujied 

 s|)igots, three give exit to treeform glands; and 

 the one farthest towards the base is connected 

 F.G.24. Middle spinneret, largely mag- ^yith a Cylindrical gland. The isolated Sl)00l 



nined. sp.c, spigot discharging cyhn- . 



iirioai giaiiii; ss, and .s.ss, spinning sp, (near l.ss.) also discharges a treeform gland. 



The middle s[)innerets are of a three faced 

 pjTamidal form. (Fig. 22, M, and Fig. 24.) 

 The bases arc directed towards the front, while their points, lying closely 

 together, are turned immediately backward. They are unjointed.^ The 

 spinning field is triangular, and occupies almost the entire slope 

 2. Middle q£ ^j^g spinneret from base to point. It contains quite a number 

 g, of long spinning spools, which may be approximately estimated 



at one hundred and fifty. On each middle spinneret there are 

 also three spinning sj^igots, of which two are close together at the tip, 

 sp.c, and give issue to cylindrical glands. A little further back, another 



B.SS 



spools of pyriforin glands ; sp.t, spigot 

 of treeform gland. 



spigot gives exit to a treeform gland, sj).t. Along the inner base 

 3. Ante- .^yQ voMS of bristles. The anterior spinnerets are of stouter pro- 

 rior Spm- ,. , • i i n n ^ • j- i • i 



portions anil more conical shape than tlie jiostenor, from which 



nerets. 



and the middle sj)innerets they are divided by quite an inter- 

 vening space. (See Fig. 22, A, A.) Their inner bases arc almost in contact 

 and are divided only by a tongue like chitinous leaf, Fig. 21, t. 

 ' See Bueliolz and Landois. Mei'kcl (U'scribes them a.s with two joints. 



