No. 2 (1917) FISH MORTALITY 59 



were all in a state of expansion and did not retract or respond 

 readily upon irritation. 



Wherever rocks are found within the bay, it was notable that 

 many small hermit crabs were found washed up dead and dying in 

 the vicinity. It was most significant that the majority of these 

 had no sheltering shell. They had obviously become so enfeebled 

 and stupefied as to be unable to retain a grip on the columella of 

 their house and had slipped out and been carried ashore. The few 

 still within shells, Trochus and Turbo chiefly, were either dead or 

 could be pulled out without resistance. This instance, together 

 with that offered by the dying off of Hippa, Donax and Cavermilaria, 

 appears to furnish the clearest evidence of the correlation of this 

 mortality with the presence of the Euglenid-infected water, as 

 all these are not vagrant forms such as the swimming crabs and 

 fishes generally ; the latter might conceivably have been poisoned 

 elsewhere and have drifted ashore into the Euglenid water, but 

 such a possibility is impossible in the case of Cavcrnularia, Hermit- 

 crabs, Hippa and burrowing Molluscs. 



On the fourth dav the mortality had decreased markedly ; men 

 no longer found it profitable to net the inshore water and the 

 number of Euglenids had sensibly decreased. This change coin- 

 cided with an alteration in the weather ; the wind had freshened 

 and it was clear that the poisonous water was being dispersed by 

 the roughness of the sea and the stronger inshore current. The 

 next day conditions had become practically normal. Later in the 

 month (9th October) similar Euglenid-infected water was seen at 

 Calicut accompanied by mortality amongst soles and ///'/j/'rt ; the 

 extent of the trouble was however insignificant and it appears that 

 the open character of the coast, with the absence of any embayment, 

 is an adverse and limiting condition against severe concentration 

 of poison water along the shore in this particular locality. 



In the bays in the neighbourhood of Quilandi and Tikkotti, a few 

 miles north of Calicut, more favourable physical conditions prevail 

 and from 9th to l6th October the presence of Euglenid water and 

 concurrent fish and crab mortality were noted, less severe but 

 otherwise similar in character to that which occurred atCannanore 

 earlier in the month. 



The specific gravity of the olive-brown affected water on 2nd and 

 3rd October when the mortality was most intense was 1026 at 81° F. ; 

 water taken on October 3rd a quarter of mile from the shore, which 



