7(5 



Part III. — Twenty-fourth Annual Report 



Fam. SalmoniDvE. 

 Genus Salmo. 



Salmo salar, Linn. The Salmon. PI. ii. b., fig. 31 ; pi. v., fig. 9. 



The earstone represented by fig. 31., pi. ii. B., measures about 7mm. in 

 length and about 3'6mm. in depth. The length of the fish they were 

 obtained from has not been recorded ; I may mention, however, that those 

 represented by fig. 9 on pi. v. are from a salmon weighing about 10 lbs., 

 but, as in the previous example, the length of this fish was not stated. 

 The earstones are of an oval form, with both ends moderately narrow and 

 bluntly pointed, but one end is more drawn out than the other, as shown 

 in fig. 9. 



Salmo (?) fario, Linn. The Brown Trout. PI. ii. b., fig. 30. 



The earstones represented on pi. ii. b. are from a trout weighing three 

 quarters of a pound, which was caught in Loch Thorn, near Greenock, 

 many years ago. 



Genus Coregonus. 



Coregonus lavaretus, Penn. The Powan (or Pollan). PL ii. b., figs. 

 25-27; pi. v., fig. 29. 



The earstones represented on pi. ii. b. are from Loch Lomond powans 

 measuring 8J inches, 8 inches, and 7J inches in length. Those from the 

 first two fishes are nearly of the same size — viz., about 5 5mm. long by 

 3mm. in greatest width, one of the ends — (?) the anterior — is moderately 

 broad and has a rounded margin, but the other end is pointed; the lower 

 margin is tolerably even, while the upper, which anteriorly is nearly 

 parallel with the lower, slopes from about the middle to the pointed 

 extremity at the posterior end. The earstones of the smaller fish measure 

 about 5mm. in length and 2 , 5mm. in depth, and these have the posterior 

 end rather more pointed than in the others. 



Genus Argentina. 



Argentina sphyrama, Linn. The Hebridean Smelt. PI. i. b., figs. 44 

 and 45 ; pi. iv., fig. 9. 



The Hebridean smelt is one of a small number of fishes that possess 

 earstones of a shape so unlike those of other fishes that there can be little 

 difficulty in determining the species the fish belongs to by the earstones 

 alone. The earstones of two specimens are represented by the photo- 

 graphs — figs. 44 and 45, pi. i. b. Fig. 9, pi. iv., gives a greatly enlarged 

 representation of those in fig. 44. The fishes from which these ear- 

 stones were obtained measured 8| inches and 8 inches respectively, while 

 the earstones themselves measured about 3'5mm. in extreme length and 

 depth — the length and depth being about equal. These earstones, which 

 differ in form from those of the other fishes mentioned in this paper, may 

 be described as broadly scaphoid or boat-shaped, the short lower margin 

 representing the keel, and the longer upper margin with its two small 

 prominences being the deck, while the obliquely truncated anterior end 

 represents the bow, and the other and nearly rectangular end the stern. 

 The extreme length of these earstones is rather more than the one-sixtieth 

 part of the length of the fish. 



