93 



either to mate with or to devour them ; but once an insect got 

 a leg or any portion of its body in the fringe around the seed 

 it was doomed. Watching a clump of grass it was quite 

 common to see an insect walk casually over a head, and sud- 

 denly commence to struggle when caught ; not one was seen to 

 escape after being caught. 



The catching of the insects appears to be purely mechani- 

 cal, and of no use whatever to the grass, whose heads have an 

 average of about 80 burrs, each of which is surrounded by a 

 fringe of prickly hairs, averaging about 50. On examining a 



Prickly Hair of Grass (greatly magnified). 



hair under the microscope it is seen to be thickly studded with 

 minute spines directed backwards ; the spines are semi- 

 transparent, and look like minute and exceedingly sharp 

 triangles of glass. There appears to be an average of at least 

 500 to each hair, or a total of 2,000,000 (80 x 50 x 500) to the 

 average head of grass. 



Some of the Tolga specimens were sent to Mr. J. H. 

 Maiden (Government Botanist of New South Wales), who 

 wrote that the grass was "Cenchrus australis, and I have 

 known of it as an insect-catching grass for a number of years, 

 but do not know how the information first came to me. I 

 think you would be quite justified in drawing attention to 

 the matter in a scientific journal." 



I have therefore thought it desirable to bring the matter 

 under the notice of the Royal Society of South Australia, 

 as I have never seen any reference to it in any publication, 

 and Mr. Turner did not refer to its insect-catching habits 

 when dealing with the species in his monograph of the Aus- 

 tralian grasses. (1) 



EXPLANATION OF PLATE IX. 



Heiads of grass with trapped insects (from photograph bv 

 Edgar R. Waite). 



(DAgri. Gaz., N.S.AV., vol. iv., p. 83. 



