28 JOURNAL OF THE 



it is far better, both for the manufacturer and the consumer, to 

 secure a product easily pulverized, with a moderate amount of 

 insoluble phosphate remaining, than one in lumps, sticky and 

 unmanageable, though nearly all soluble in water. Reversion 

 takes place very quickly in the soil any way, and diffusihility is 

 of prime importance. 



CONTRIBUTIONS FROM THE BIOLOGICAL LABORATORY OF THE UNIV. OF N. C. 



No. XIII. 



NEW INSTANCES OF PROTECTIVE RESEM- 

 BLANCE IN SPIDERS. 



GEO. F. ATKINSON. 



Within the past two years two interesting eases of protective 

 resemblance have come under my observation. A small species, 

 Thomisus aleatorius Hentz, is remarkable for having the two 

 anterior pairs of legs very long, while the two posterior pairs 

 are very slender and short. The spider is very common on 

 grass. One summer day, while reclining in the shade, I watched 

 an individual of this species as it passed from one culm to an- 

 other. Soon it ran up the stem a short distance and suddenly 

 disappeared from view. For some time I was greatly puzzled 

 as to the manner of its disappearance. Upon close scrutiny, 

 I saw the spider clinging with its posterior legs to the stem. 

 Its two anterior legs on each side were approximated and ex- 

 tended outward, forming an angle with the stem, strikingly 

 similar to the angle formed by the spikelets. 



An undescribed species of Cyrtarachne mimics a snail shell, 

 the inhabitant of which during the summer and fall is very 

 abundant on the leaves of plants in this place. In the species 

 of Cyrtarachne the abdomen partly covers the cephalothorax, is 

 very broad at the base, in this species broader than the length 

 of the spider, and rounds off at the apex. When it rests upon 

 the underside of a leaf with its legs retracted it strongly resem- 



