HARD 1VICKE' S SCIENCE- G OS SIP. 



227 



chiefly from the following fact. Many of the coral 

 masses on the plain are very much undermined by the 

 •action of water, which action can be seen still at work 

 round the harbour. From high-water mark seaward 

 the water deepens gradually to about three or four feet 

 just inside the edge of the reef, then shallows slightly 

 immediately over the edge, then drops suddenly to four 

 •or five fathoms deep. The part between the edge of 

 the reef and the high-water mark is slowly filling up 

 •with disintegrated coral debris and sand drift, and is 

 also being raised by upheaval, which latter action 

 seems to be intermittent rather than continuous. It 

 •would be extremely interesting if continuous observa- 

 tions on the growth, etc., of the coral were made at 

 some such place as this. Everything is favourable 

 for such observations to be taken, either in this port 

 or at Suakim. Most curious is it to note how in 

 some places the edge of the coral reef may be quite 

 close to the high-water mark, while in other places, 

 at some distance off. Possibly this may be owing to 

 the way in which the tide currents strike the reef, in 

 some places continually bringing in fresh supplies of 

 food, in others reaching the reef after being exhausted 

 of food supply. On the seaward side of the 

 coast there is a long line of coral islands, with 

 a deep water channel inside, and I cannot help 

 thinking that by the same process these too 

 will be gradually joined to the mainland, not 

 so rapidly, unless there is more rapid up- 

 heaval, for the alluvium will have farther to 

 travel. Earthquakes are by no means rare 

 phenomena here, and signs can be seen in 

 Massaua, as cracked buildings, etc., which 

 testify to the severity of the shocks. 



3. Vegetation.— On my arrival towards the 

 end of November there was very little vegeta- 

 tion on the plain, but it very soon began to 

 sprout up in the most marvellous way, and, at 

 the beginning of February, not only the plain 

 but also the hills looked quite green and nice. 

 'Scattered about the plain were clumps of large 

 cacti up which climbed several kinds of 

 creepers, and then there was a large fleshy- 

 leaved shrub with a handsome yellow flower, 



said to be poisonous. There are dozens of pretty 

 little flowering plants which seem to spring up as if 

 by magic, out of what appears the most barren soil, 

 though undoubtedly it does look so barren, yet it is 

 very rich and with irrigation would grow almost 

 anything. There are only a very few trees, and 

 these have been planted and have to be well cared, 

 or else the summer heat would soon shrivel them up. 

 Although summer and winter are at the same time 

 here as in England, yet their effect upon vegetable 

 and animal life is practically reversed : plants flower, 

 and animals breed in the winter, in summer all is 

 quiet, no vegetation, few animals and no insects, 

 all is at rest, owing to the intense heat. 



4. Zoology. — It is chiefly owing to the lack of 



surface water that the fauna is so poor : of animals a 

 species of hy;ena, a small gazelle, called by the 

 natives "Dig Dig," a ground squirrel (Xerits rutilus), 

 a small jerboa, and a small bat were all I saw. At 

 times leopards are seen in the neighbourhood, but 

 they are becoming rare now. 



David Wilson-Barker. 

 66, Gloucester Crescent, Regent's Park. 



[To be continued.') 



THE WATER-SPIDER {ARGYRONETA 

 AQUATIC A). 



THROUGH reckless collectors and would-be 

 aquariumists not knowing, or taking proper 

 precaution as to the natural habits of the water- 

 spider, and the insertion of more voracious enemies 

 in the same compartment, has probably arisen the 

 scarcity of this amusing aquatic creature. 



Yet, when in captivity, its movements may be 

 watched with facility while spinning from plant 



Fig. 85. — Female of water-spider [Argyroneta aquatka) 



Fig. 86. — Cocoon of Argyroneta aquatka. 



to plant its fine webby path, and occasionally ascen- 

 ding to the surface of the water to refill with air 

 the silken envelope with which its body and respi- 

 ratory organs are so wonderfully provided, for its 

 existence while under water ; then, the fact of its 

 hinder legs guarding the silvery-like bubble with 



