1969] 
Levi and Levi — Sicarius 
35 
digging, but did not fit herself into the hole. This observation cor- 
responded with that of the first eggcase construction. But now with 
strong movements of the first and second legs, the spider began 
throwing sand io cm back, toward the eggcase. The sand noisily 
struck against the paper lined plastic wall of the container. It was 
first thought that this action was to fill the hole in the sand under the 
eggcase, the hole produced by throwing sand back for the eggcase 
construction. But the spider continued changing her position around 
the eggcase, always remaining about io cm away, throwing sand 
toward the eggcase. The accuracy was not great and often the sand 
was thrown at an angle 45 0 off. But the spider must have been able 
to determine the direction of the eggcase from her changing position. 
The throwing back of sand reminded one of a dog digging a hole. 
The motions were those illustrated by Reiskind (1966, Fig. 1). By 
11 130 a.m. the eggcase was buried under several cm of sand (Fig. 6) 
and the female dug herself into the sand and disappeared. 
From the start to completion it took the spider 11 days — perhaps 
prolonged because of the disturbance. However, the spider continued 
construction and did not start out anew as might have been expected. 
Four days after completing the work the female was found dead on 
the sand surface. The cause of death is unknown. It may have been 
dehydration resulting from frequent disturbance. 
Preserved Sicarius were examined under the microscope. Unlike 
juveniles and males, adult females have their spinnerets almost hidden 
by a crown of long setae many layers thick. Only the posterior spin- 
nerets show (Figs. 7, 8). ( Sicarius lacks the large colulus charac- 
teristic of the related Loxosceles.) Under the microscope the setae 
were found to be feathered (Fig. 9) and about 1 mm long. A needle 
run through these setae became dusty. To test the assumption that 
these setae can pick up sand mechanically, one female preserved in 
alcohol was dried and the spider’s abdomen was rocked in the sand. 
No sand grains were picked up at all — only dust ? the particles about 
1/10 the diameter of sand particles. And, indeed, the particles in 
the wall of the eggcase were all much smaller than the majority of 
the sand grains in the spider’s container. The setae around the spin- 
nerets sift out the right size particles from the sand thrown back by 
the female. The sand grains were later measured and found to be 
0.2 - 0.4 mm in diameter. Some of the fine particles that washed off 
the female, preserved in alcohol after she died, measured 0.02 - 0.06 
mm diameter. Some of these particles may have come from setae on 
other parts of the female’s body to which dust clings readily, giving 
the animal the color of the background. The difference in grain size 
