KEPORT ON THE PELAGIC HEMIPTEEA. 21 



referrible, partly to H. Wiillerstorffii and partly to a new species. What the others may 

 be, I of course cannot say, but it is not improbable that there are other species amongst 

 them.— F. B. W.] 



XVII.— Robert M'Lachlan, F.R.S. 



The Entomologists Monthly Magazine, voL viL 1870-71. 



After giving a summary of Professor Giglioli's paper, the author proceeds to say : — 

 " These notes have a peculiar interest for me, as exciting reminiscences of a voyage of 

 thirteen months' duration I made when a youth, in 1855-56. This voyage was marked 

 by a most immoderate amount of calms (in one case extending to thirty consecutive 

 days, in the hottest part of the China Sea), and I lost no opportunity of fishing up — and, 

 I am sorry now to say, casting away, — the, to me, wonderful forms always floating 

 around. Long before crossing the line, on the outward voyage, I was struck by small 

 whitish creatures which often appeared coursing with great rapidity over the surface of 

 the ocean ; at length one was captured, and I well remember my astonishment on finding 

 it was a spider-like insect, of the affinities of which I then knew nothing. They disap- 

 peared, or rather were lost to view, as soon as a breath of wind caused a ripple on the 

 surface, but were common in that most unpleasant form of sea-disturbance in which there 

 are great ' smooth ' waves, the efi'ect of a recent storm, but with no present wind. In 

 the Atlantic, Indian, and Pacific Oceans, it only needed the required state of the sea to 

 bring these merry coursers to view, and certainly often without the presence of the smallest 

 piece of floating sea-weed. Those who have voyaged will bear me out when I say that, 

 excepting in the mysterious Sargasso-sea, in the course of the oceanic currents, and in the 

 vicinity of land, sea-weed may be looked for with as much chance of finding it as daisies. 

 I should here state that the brilliant white appearance of the insect on the ocean is caused 

 Ijy the pellicle of air that surrounds it, the creature itself being blackish. If these notes 

 should be read by any one of those ' who go down to the sea in ships,' I would remind him 

 that, if he can throw any light upon the life-history of this most wonderful insect (how 

 many species there may be I know not), he will confer the utmost benefit upon natural 

 science. The Trichodesmium alluded to by GiglioH is a minute confervoid plant which 

 sometimes covers the surface of the ocean like fine sawdust." 



XVIII. — Professor Karl Semper. 



The Natural Conditions of Existence as tliey affect Animal Life, p. 144; also note on p. 434, 

 1881. 



" In the Pacific Ocean and Philippine Sea I have myself often found various insects and 

 even spiders in the sea, sometimes swimming in great numbers on the surface, sometimes 



