CEUSTACEA OF NEW ZEALAND. 263 



more carefully examined than the majority of surface or marine species, and a fuller 

 examination of the latter will perhaps show that many of them are as well supplied 

 with sensory setae as the subterranean species. 



The Food of Subterranean Animals. 



The source of the food-supply for the animals living in caves and underground waters 

 is a question of miich interest and of considerable difficulty. Almost all writers on the 

 subject speak of the food-supply being very scanty, and yet the animals, though of 

 course few in numbers compared with those living on the surface of the earth, are 

 yet numerous, and when captured do not look particularly ill-fed. According to 

 Packard [83, p. 24] the blind fish of the caves of North America probably live on the 

 blind crayfish and the Crangonyx, and perhaps the Ccecidotcea, and the crayfish also lives 

 on C(Bcidot(Ba ; so that, confining our attention to the Crustacea, the question is narrowed 

 doAvn to the food of CraHfjoni/x and Ccecklotcea, viz. animals similar to those found in 

 underground waters of the Canterbury Plains. As Packard points out : — " It goes 

 without saying that there are no truly vegetable-eating animals living permanently 

 in the caves ; no plant-life exists (except in rare cases a very few fungi, and most of 

 these probably carried in by man) in the caves on account of the total darkness " 

 [83, p. 25]. 



Crangonyx and Cfpcidotma are hence probably mainly carnivorous, but what they find 

 to eat is a great puzzle. Packard suggests that they may devour their own young ; but 

 what the young find to live on he considers still more difficult to conjecture, as rotifers, 

 infusoria, and copepods are so very scarce. Cope, writing of the fauna of the Wyandotte 

 Cave [30, p. 13], states : — " As to tlie small Crustaceans, little food is necessary to 

 support theu- small economy, but even that little might be thought to be wanting, as we 

 observe the clearness and limpidity of the water in which they dwell. Nevertheless, the 

 fact that some cave-waters communicate with outside streams is a sufficient indication 

 of the presence of vegetable life and vegetable debris in variable quantities at different 

 times. Minute freshwater algae no doubt occur there, the spores being brought in by 

 external commimication, while remains of larger forms, as confervae &c., would occur 

 plentifully after floods." 



Still the supply imported in this way must be very scanty, and as an illustration of 

 the general poverty of the food-supply in the caves Packard mentions that in the 

 Wyandotte Cave the common ^lyriopod was found gathered around the hardened di'ops 

 of tallow which strew the pathways of the cave *. 



Concerning the food of the Niphargus found in the well at E-ingwood, Hogan, quoted 

 by Stebbing [108, p. 316], remarks : — " Some water drawn from the pump at Ringwood 

 has been proved by microscopical examination to contain numerous animalcules; and 

 this will probably turn out to be the case with all the waters in which Niphargi are 

 found." 



The facts bearing on this subject that I have observed in connection with the New- 



• "The Cave-Beetles of Keutucky," American Naturalist, x. (1876) p. 285. 



