37 



that these eggs were found in this way seems to indicate that 

 there is some\gent of destruction at this stage, <" P^b^bly 

 these eggs when they sink to the bottom of mud or sand 



'"xheTarva'whi^h'is hatched out from the eggs seem to be 

 much mo.e Uable to attacks of enemies, P^^.X^P^ ™ -«'™'^° 

 the oresen-e of the unconsumed yolk granu.es. By way of ex 

 nerimen some eggs and larvs, some hatching and some just 

 Tatched :ere pufinto a tank containing harders muUet^^ and 

 were at once attacked and devoured In »"« ^ase two or 

 three female crawfish were kept in a large t=^"l-T'*^',f fe,T 

 kinds of fish, and it was repeatedly observed that small hsh 

 more especially KUp-fish (various species of Chnus), were con 



ZtmuTli; onVe Ltch during the ^^^^-^^"l^^^Z^'Zl 

 round the female and devouring many of the larvfe as ttiey 



were shaken off. 



"ortr^ther hand, the larv. when past their /^^ -ge 

 and dispersed in the water do not seem to suffer from the 

 aUacks of fish. Thus when a few active transparent larv=e 

 were placed m this tank they seemed to completely escape 

 the notice of the fish or at least were unmolested. Two or 

 hree small gobies in the crawfish tank remained quite m- 

 differen"even when the larva; scattered in hundreds through- 

 out the tank almost touched their snouts. As noted under 

 habits of the young crawfish at this stage, their behaviour also 

 seem to indicate that they had little cause to fear the 



""TTsum'up.Th'crawfish produces many thousands of eggs 

 whlh Zy b'e' devoured by fish^ The early '-v- st, 1 opaqu 

 and eess which are shaken off in clouds by the female are 

 specially Ibble to attack and are probably destroyed m large 

 numbers At a later stage when the larva, now transparent, 

 arTwSdy scattered throi^ghout the water they would appear 

 to be comparatively immune from attacks. At a later stage, 

 'however when the^arv. take to the ^0117^-^^-0- 

 opaque and pigmented, they are agam hable to the attacks 

 of their enemies, notably the octopus. 



Lastly the adult stage seems agam to be bettei able to 

 defend ft'self and to have comparatively ^ew -e-es wilh the 

 exception of man. For the depredations of the hsh and tne 

 :ctoPnatre has made provision by produang a surplus 

 of progeny for these natural enemies, and on the whole tne 

 c aS cL maintain its own, but it has -"^P^™- 

 for the depredations of man at a stage when fewer natural 

 nemies are present. Hence it is that this new dram in the 

 supply so quicklv upsets the balance, and, in spite of the 

 [C.P. 5— 'I3-] 



