JUAN VI N AS— THE WATERFALLS 20l 



transportation that goes a long way to explaining the sudden 

 appearance of large numbers of diatoms in new localities. 

 I therefore look upon this rather abundant flora on the 

 minute leg of this aquatic insect as of some scientific impor- 

 tance. Of course in this case the power to fly does not exist 

 until a later period of development, but many of the water 

 beetles and other insects are doubtless coated with living 

 diatoms in the same way." Professor Mann's letter led to 

 the scraping of the legs and bodies of our adult specimens of 

 Thaumatoneura and in this minute quantity of "dust" he 

 found about sixty diatoms, thus confirming his conjecture 

 as to the part insects play in spreading these unicellular 

 plants. 



Other insects lived at the waterfalls. At one, on June 24, 

 we secured an extraordinary little creature, something like 

 a leaf-hopper, equipped at its hind end with a long thick 

 brush of iridescent hairs, which could be spread open. The 

 brush was half an inch long, the insect itself only one-quarter 

 inch. When A. first saw it, it had alighted on her knee and 

 exactly resembled a pappus-crowned fruit like that of 

 dandelion or of thistle. Such she thought it was and put 

 out her hand to brush it away when the supposed seed leaped 

 into the air and settled in another place. It proves to be a 

 member of the family Fulgorid^. Very likely the brush 

 of hairs (which are really secreted waxy filaments) do serve 

 the same end as the hairs or pappus of the fruits of the 

 Compositse — distribution by means of air currents. 



On the rocks below the waterfalls — and in other rocky 

 streams — were many tiny crickets known as Rhipipteryx. 

 The most common species {R. biolleyi) — and it was very 

 abundant in the situations mentioned on August 3 — was 

 about 7 mm. (.28 inch) long, with body and wings black, 

 prothorax and front wings edged with cream-color, some 

 white marks on the head, but the legs orange-red, so that 



