184 DE. C. CHILTON ON THE SUBTEERANEAN 



have been brought up, catching any that there may be with a dippiug-tnbe, and pumping 

 the bowl full again after the lapse of a few minutes ; and where the Crustacea have been 

 fairly numerous I have found this intermittent method of pumping more successful than 

 continuous ])umping. In other wells where the Crustacea were fpund only sparingly, 

 Mr. Smith of Ashburton found it better to collect them by tying a muslin net over the 

 spout of the piimp ; and in order to prevent the animals being injured he floats the net in 

 a bucketful of water, the bucket being raised so that the level of the water in it is liigher 

 than the spout of the pump. 



Mr. Smith reports from Ashburton that all the subterranean animals appear to have 

 been brought up by the pumps most abundantly some eighteen months or two years ago, 

 when, owing to the continued drought, the water in the wells was sinking ; but that 

 since the wells were sunk deeper, and up to the present time when the water is now 

 rising atrain in most wells, the animals have been much rarer. Thus in one of his letters 

 he says : — " I generally enquire wherever I go if any animals come up in the water, the 

 answer being that there were plenty twelve months ago hut none lately." In another he 

 says that one gentleman informs him " that they frequently saw minute ' pale shells with 

 white slugs in them ' before the pump went dry eighteen months ago; since sinking the 

 pump 15 feet more, they have not detected any animals in the water." In another letter, 

 dated 29th June, 1892, Mr. Smith says Mr. Dolman, a practical well-sinker of the district, 

 informed him " that he had not seen a single animal in well-water for some months. 

 There is, however, not much well-sinking going on, as the water is almost up to its usual 

 height." 



My own experience tends to strengthen the conclusion that the animals are brought up 

 most abundantly while the level of the water is sinking, for I found them very abundant 

 at Eyreton from 1881 up to about 1886, during the whole of which time the water was 

 sinking, and the wells had to be deepened several times. I have had few opportunities 

 of collecting at Eyreton since, but I am told that very few animals have been seen during 

 the last two or three years. In 1891 Mr. R. M. Laing sent me quite a number of sub- 

 terranean Crustacea from one of the Avells at Leeston, and he states in a later letter that 

 the well has since become dry. 



Erom the one well at Eyreton in which I first noticed the Crustacea I have collected 

 the following five species : — Qammarus fragUis, Crangomjx compactus, CalUopius suh- 

 terrancus, Cruregensfontunus^ and I'hreatoicus typicus. Of these CalUopius subterraneus, 

 the female, has always been much more abundant than any of the others ; for two or three 

 years from 1881 I seldom had to pump for more than 10 or 15 minutes without obtaining 

 some specimens of this species. After the well was deepened it was less abundant, and 

 did not preponderate over the others so much as before. The male of this species is very 

 rare ; I have seen only about half a dozen specimens altogether. "Whether this species is 

 really so much more abundant than the others in the underground waters is, perhaps, a 

 little doubtful, as from its smaller size it would naturally be drawn up the pijie more 

 easily than the larger forms. Of the other species, Gammarus fragilis and Crangonyx 

 compactus have been about equally abundant on the whole, but sometimes one form has 

 preponderated and sometimes the other ; Gruregens fontanus, though somewhat numerous, 



