CEUSTACEA OF NEW ZEALAND. 251 



vegetation, and that they have been the recipients of all the leakage of the hills throughout 

 all the ages that have passed since the sea retired, it appears to me that the deeper leads 

 must be satui-ated with water right through from the mountain-foot to the Australian 

 Bight. For, however slow the circulation of the system may be, as the water has never 

 ceased to run in at the upper ends of the region, and as it does not rise to the surface as 

 springs, it must run out at the lower end into the sea, escaping in the form of submarine 

 springs. As a matter of fact, along the south coast of Australia, between Warrnambool 

 and the Murray mouth, the sea literally bubbles up with fresh water which has leaked 

 up through the sea-sands " [52, pp. 235, 236]. 



Doubtless a large portion of the deeper underground waters of the Canterbury Plains 

 escapes into tlie sea in the same way by submarine springs, for in many cases they are 

 known to be much below the sea-level. Thus the water-bearing stratum that supplies 

 the ordinary artcsians of Christchurch is, at the coast at New Brighton, 136 feet below 

 the surface, and there is another stratum below at about twice that depth [63, p. 33]. 

 Other portions of these underground waters in Canterbury rise to the surface, before 

 reaching the sea, as springs, like those which form the source of the river Avon near 

 Christchvu'ch. 



Tacts like those quoted above from Mr. Griffith's address, and the widespread distri- 

 bution of the subterranean genus Nijjhargus in Europe, and of the closely-allied genus 

 Crangonyx in North America and elsewhere, remind us of what might otherwise be 

 overlooked, viz. the universality and great extent of underground waters. An instructive 

 example is given by Wallace in his ' Malay Archipelago ' : — 



" The little island of Kilwaru is a mere sandbank, just large enough to contain a small 

 villaae, and situated between the islands of Ceram-laut and Kissa — straits about a thii'd 

 of a mile wide separating it from each of them. It is surrounded by coral-reefs, and 

 oilers good anchorage in both monsoons. Though not more than fifty yards across, 

 and not elevated more than three or four feet above the highest tides, it has weUs of 

 excellent drinking-water — a singular phenomenon, which would seem to imply deep- 

 seated subterranean channels connecting it with other islands " [114, pp. 375-6]. 



Many similar facts have been brought to light in coimection with the boring of artesian 

 wells, and some of these will be found collected in Lyell's ' Principles of Geology ' [76, 

 vol. i. p. 385 &c.], where it is shown not only that the underground waters extend to 

 great depths, often far below the level of the ocean, but that various distinct sheets of 

 water maj be met with, one below another, five distinct sheets having been intersected 

 in a well at St. Oueu, in Prance [76, vol. i. p. 3S9]. Lyell also gives some examples 

 showing that there are often open passages by which the subterranean waters circulate. 

 Thus, in a well at Tours, from a depth of 364 feet, there were brought up a freshwater 

 shell, some land species, some seeds of plants and other vegetable matter, all of which, it 

 was supposed, had flowed from some valleys of Auvergne or Vivarais, distant about 150 

 miles, since the prcceduig autumn. After giving other examples of a similar kind, Lyell 

 says, "we see evidence of the water not having been simply filtered through porous rock, 

 but having flowed through continuous underground channels. Such examples suggest 

 the idea that the leaky beds of rivers are often the feeders of springs " [76, vol. i. p. 391]. 



SECOND SERIES. — ZOOLOGY, VOL. VI. 33 



