Manclicster Memoirs, Vo/. hu'. (i()i2), No. II. 5 



Hitherto tlie scales used for this study have been taken 

 from what is known as the shoulders of the fish ; that is, 

 from the area midway between the dorsal median line and 

 lateral line, and between the dorsal fin and the operculum. 

 The enumerations of the annuli were made, as Mr. Johnston 

 tells us, " a little to one side or other of the long axis of 

 the scale." (See Diaq: i, F/^i^ 5.) So far, no .systematic 

 examination of scales from different parts of the same fish 

 has been published. A systematic examination seems to 

 be an essential preliminary to accurate work, for how can 

 comparisons be rightly made of scales from different fish 

 when the extent of variation on one fish is not known ? 

 In order that this might be done, Mr. J. Arthur Mutton 

 very kindly supplied a lolb. fish caught in the nets of 

 the estuary of the Wye on August ist, 19 10. From this 

 fish scales were collected from fourteen positions, seven 

 of which are shown in Diag. i. Fig. i, the other seven 

 being corresponding positions on the right side of the 

 fish. The number of annuli on one scale from each of 

 the seven positions on the left side of the fish was ascer- 

 tained, and measurements were taken of the distances 

 from the centre to the periphery along both the long and 

 short axis. In order that these results might be more 

 accurate, a specially marked eye-piece was used. (See 

 Diag. I, Fig. 4.) The scales were cleaned in water and 

 mounted with the internal side downwards. By this 

 means, as all the scales are taken from the same side of 

 the fish, comparisons can be made between the dorsal 

 and ventral sides of the different scales. Placing the 

 slide on the stage of the microscope so that the centrum 

 of the scale came under the point on the marked 

 eye-piece, which in the Fig. is called A, and the long axis 

 (see Diag. i, Fig. 5) along AB, calculations were made 

 along the lines AB and AC, taking into account every 



