n8 MARVELS OF FISH LIFE 



as before the fillets were removed, and the relative 

 position of the bones of the body, the head and fins 

 remains the same. If all the skeletons which have been 

 thrown aside are gathered at the end of the day, it will 

 be found that they can be divided into groups of certain 

 sizes. In the month of May, I found that the plaice 

 in my fishmonger's shop, with very few exceptions, 

 could be divided into three groups, namely, a group of 

 fish from fourteen to fifteen inches in length, another of 

 about eighteen inches, and lastly, of fish from twenty 

 to twenty-one inches. I took twelve fish from each of 

 these groups and by examining the otoliths could read 

 quite clearly that these plaice were respectively five, 

 six and seven years old. I have never seen otoliths 

 scientifically removed, but it is a very easy matter to 

 get out the right and left otoliths in a few minutes from 

 a number of plaice. 



Put the plaice on a board on its left or colourless 

 side. Take the fishmonger's largest knife and lay the 

 edge of it along a line from the upper margin of the 

 pectoral fin to a point an eye's breadth above the upper 

 eye ; then strike the back of the knife a sharp blow with 

 a mallet and cut right through the head. 



You will find that you have opened up a hollow 

 space in the skull which is the front part of the cranial 

 cavity. The back part of this cavity still has a dome- 

 shaped covering of soft bone over it. Slip the point of 

 a smaller knife under this dome-shape covering and cut 

 directly upwards. Then pull open this back part of 



