POMOXA f'()I.I.Ef;i; JotRXAI, OP KxTOMOI/MiY 811 



sonsiitioii. aUliouj;li proliaMy scrviiiK' a vi-ry ditTcrciit puriiiisc and stiniiilatin(( 

 a dillVrcnt part of the nervous system, perhaps part of the siih liypoilennal 

 nerve plexus knowu to oeeur in many artliroptxls. These minute hairs will 

 Ite eonsidereil at this time only in so far as they may represent parts of hollow 

 sen8t)ry seta'. 



One of the most noticeable features of tarantula is the >;reat ahundanee 

 of Ions; hairs. The.se are espeeially numerous on the lej;s and alidomen hut 

 may he found on all jjarts. Two general types may he reeo)j;ni/.ed at onee. 

 Ions rather lar^e seta- often brown or of a red eolor and short ilark ones 

 often ma.s.seil together antl giving; the appeara!iee of black velvet. Moth of 

 these are hollow and seem to be simply f;reatly modified haii-s of the ins«'et 

 type. The lont; brown or red hairs of tarantula are the most eonspieuous. 

 Some of these are as long as six mm. They are strongly ehitini/eil. rather 

 slender, with a large eavity whieh is usually somewhat larger at the base. 

 ICspeeially towards the tip, along the shaft, a tine pubeseenee is evident. In 

 Figure 255, 1, there is shown a hair of this typo. Near the joint-s of the h-g 

 there are fewer shorter, heavier hairs, almost spines, siieh as shown in Figure 

 255, 2. Between the long and heavier hairs of the legs and body there are 

 luuiierous fine set-in whieh are (piite plume-like lH'eaus4' «d" the numerous 

 tine ehitinous branches extending off from the shafts of the hairs. 

 Sueh a one is shown in Figure 255, '.i, while Figure 255, 4, is a snuiller one 

 from a leg. It is these seta- or hairs similar to them, that cause the legs and 

 liody to appear dark. Modifications of this sjime type are found densely 

 ma.s.sed on the feet or other extremities where the dark velvet appearance is 

 most marked. These hairs are often enlarged or tlattened at the tip. Figure 

 255, 5, G and 7, are of this sort. 



.N'ear the mouth there are a number of long and short rather red hairs 

 with very little pubescence upon them. A snuill one of these is shown in 

 Figure 255, 8. Some of these red hairs about the mouth are much like the 

 usual type, but numy are long, slender and in .stune eases tlattened somewhat. 



Comparison was made between the seta- of tarantula and other spitlers 

 from a number of dilTerent families. In all, the usual type of seta was found, 

 and the plume-like hairs, although less abundant, were found in almost every 

 representative. Figure 25(). 1 and 2, are from one of the Lyeosidie. The 

 first figure was taken from the back of the abdomen and was much like some 

 of those of tarantula, but was not so abundant. The second was a large hair 

 "f tile simple type from a leg. 



Figure 255, U, 4 and 5, are from the Kpeiridie, Kpt ini iji tnmn ; 4 from the 

 caudal end of the abdomen is a simple hair with a high base. 



Figure 255, H, 7 and 8, are from the ThomisidiV (Thaiialiis sp.) where, 

 in addition to the usual tyjie of simple hair there are at least the.se three sorts 

 of setie with side projections; ti, from the abdomen, is a short plumed hair 

 with thicker projections also; 7 is a short plumetl hair; 8 is a setji with sec- 

 ondary projections on one side. This last st>rt is verj' abundant on the legs. 



