THE LOBSTER AS A TYPE OF CRUSTACEA 25 



and affect the nerve-endings within. These hairs are 

 known as " olfactory filaments." 



The sense of taste in aquatic animals is, perhaps, 

 not sharply defined from that of smell, but it is 

 not very rash to assume that certain hairs on the 

 mouth parts and on the fleshy upper and lower lips 

 which bound the opening of the mouth have to do 

 specially with this sense. 



The relative importance of the various senses in 

 the Lobster is well illustrated in the following account 

 of its habits given by Dr. H. C. Williamson in the 

 Report of the Scottish Fishery Board for 1904. 

 After noticing that, in daylight at least, the Lobster 

 appears to be " purblind," only distinguishing light 

 from shadow, Dr. Williamson goes on : " It tests 

 a shadow with its antennae, or sometimes, when a 

 strong shadow is thrown on it, it jumps at it with 

 its chelae outstretched and snapping. It is dependent 

 on its antennae for guiding it in safe places. It 

 is especially careful in testing any hole before it is 

 satisfied with it. It discovers the cavity by means 

 of its antenna, which is waved well out to the side 

 and in front as it walks. It searches the innermost 

 depths of the hole with the antenna, and then inserts 

 its chela. If the examination with the chela is also 

 satisfactory, it immediately turns and backs smartly 

 into the hole. In feeding it is guided to the food by 

 the antennules. A piece of food which is dropped 

 near a Lobster may fall quite unnoticed unless it 



