AS AN INDEX OF AGE. 55 



Dr. Marett Tiins's facts may be affirmed by the publication of his detailed 

 paper, to which I look forward w^ith much interest. 



[Since Mr. Thomson left for Soutli Africa, Mr. A. W. Brown, of St. 

 Andrews, has been good enough to send me a reprint of a note communicated 

 by him to the Royal Society of Edinburgh {Proceed. Roy. Soc. Edinburgh, 

 1902-3, p. 437), entitled "Some Observations on the Young Scales of the 

 Cod, Haddock, and Whiting before Shedding." This note is as follows : — 



"During the winter of 1902-3, I conducted observations upon the scales 

 and their condition, in several of the gadoid fishes. Investigation was com- 

 menced in October, 1902; but it was not until the beginning of March 1903 

 that the first appearance of the young scale took place. In stained specimens, 

 it can be recognised as a deeply staining ' nucleus,' lying beneath the old 

 scale, just under its centre. Such an appearance was found in cod, haddock 

 and whiting of all ages from one to three or four years; and, in all, the 

 young scale is clearly recognisable, underlying the old. As soon as these 

 fishes have spawned, they appear to shed their scales, the epidermis first 

 peeling oif. An examination of a few large haddocks, eight pounds weight 

 and over twenty-seven inches in length, showed that in January the ovary 

 was black, shrunken, and not in spawning condition. I am inclined to think 

 that these fish are past the age for spawning. I examined very carefully 

 this class of haddock right on till April. In every case I found that the 

 scales showed evidences of hard wear, and in some cases were frayed. In 

 these fishes no traces of the replacing scales were found, and the probable 

 conclusion is that no further shedding of the scales takes place after the close 

 of the reproductive period. 



" It has been suggested that the annual rings of growth may be traced 

 upon the gadoid scales; but 1 find that upon the cud, haddock, whiting, 

 green cod, and pollack, of one to three years of age, scales may be obtained 

 from difi'ercnt parts of the body showing ninety, sixty, or thirty rings, 

 according to the part selected. 



" I have been enabled to trace back the first appearance of the new scale 

 to the month of February, when it may be recognised as a dark tip growing 

 upon a small papilla. 



" By the middle of April, the epidermis on the head commences to peel off, 

 and, probably somewdiat later, over the body. The details of this process 

 will have to be followed in sections ; but sufficient evidence is to hand to 

 make it probable (1) that gadoid fishes shed their scales immediately after 

 spawning; (2) that after the age limit of spawning is reached no further 

 shedding of scales takes place ; (3) that the concentric rings of the scales do 

 not represent annual increments, but must have other causes." 



Mr. Thomson had heard verbally of this communication, but had not seen 

 the note. He states that the presence of minute scales amongst the larger 

 ones in the trout was described and figured by Klaatsch in 1891, and their 

 presence in Gadidae has been known to him for two years. He refers to 

 these small scales in another part of this paper (p. 57), and does not attach 

 to them the same significance as that given them by Mr. A. "W. Brown. 

 — E. J. A.] 



