343 



Timor on his way to the Cape, and the present record is 

 apparently the first for Australia. It seems probable that 

 the fish had attached itself to the Norwegian vessel in the 

 Indian Ocean, bound for Adelaide, and when in dock trans- 

 ferred its patronage to the "Falcon." 



The chief operative factor in the distribution of pelagic 

 fishes is that of temperature, and as the fundamental host 

 of the sucker fish is some larger fish or mammal, it may be 

 presumed that the limits of endurance of temperature as 

 enjoyed by the host is approximately that of the commensal 

 also. 



Though a certain amount of discretion in the choice of a 

 host is doubtless indulged in by the sucker fish, it is believed 

 that some species are specially "attached" to specific animals 

 or fishes. In the case of a species that exhibits less dis- 

 crimination its range is likely to be greater, but the inter- 

 esting question arises as to what happens when the fish 

 attaches itself to ocean craft ? When the vessel is moving 

 north or south the change in temperature is likely to provide 

 the first element of discomfort, but if the vessel maintains 

 approximately the same latitude, the absence of the supply 

 of usual food would doubtless be an early factor in the mis- 

 placed attachment of the sucker fish. 



EXPLANATION OF PLATE XI. 



Disc of the sucker fish (Echeneis ausfralis, B<:'nnett), from a 

 cast (seven-eighths natural size). 



