of the Fishery Board for Scotland. 



51 



in a large proportion) from the pelvic fin to the anal aperture (Cuvier and 

 Mitchell 33, Couch 35). In the young herring the numbers are from 26 

 to 29 between the head and pelvic fin, and 13 to 15 between the pelvic 

 fin and the anal opening. The scales forming the lateral line are also 

 more numerous in the herring than in the sprat, the herring having 56 to 

 58 (generally 56), and the sprat 48; while of transverse scales the herring 

 has 16, the sprat 11 or 12. 



The position of the dorsal and pelvic fins with respect to each other 

 affords a very sure guide to the determination of the species of sprat and 

 herring. In the sprat the pelvic fin is anterior to the first ray of the 

 dorsal; while in the herring it is posterior to it. Wilson, in his short, 

 and, so far as it goes, very correct definition of the sprat and young 

 herring [Report of the Fishery Commissioners for the year 1866), men- 

 tions this characteristic as being less perceptible than the jagged belly, or 

 the difference in size of the eye, whereas my conclusions, at least in 

 respect to the latter, are the reverse. Tor I find the size of eye very 

 deceptive and difficult of definition, while the position of the fins is 

 unmistakable and certain. Although, as I have already stated, the fins 

 vary in their position relatively to themselves, and also in their actual 

 position on the body, the pelvic fin in the sprat varying (irrespective of 

 the size of the fish) from 3 mm. in front of the dorsal to almost nothing, 

 yet it is never found posterior to the dorsal, just as in the herring it is 

 never found anterior to it, although it may vary (in the young herring) 

 from 1*5 mm. to 5 mm. in its distance behind the dorsal. 



The variation in the position of the other fins, of course within a cer- 

 tain rather narrow limit, is almost endless, and it is quite useless to 

 attempt to fix their position with respect to each other so accurately as 

 Parnell does, when he says of the herring, that the base of the ventral 

 fin is under the sixth ray of the dorsal. Mitchell (Hist, of Her.) gives 

 the position of the dorsal fin as half way between the point of the upper 

 jaw and end of longest caudal ray, which in. itself is a varying point on 

 account of the wear and rubbing to which these rays are subjected ; but 

 whilst this was the position in which it was placed in one or two of the 

 specimens which I examined, I found the fin generally to be situated 

 further forward ; and while unable to fix any absolute position for it, I 

 noted that in the larger number of cases the first ray of the dorsal fin was 

 about half way between the tip of the premaxillse and the fork of the 

 tail or end of the middle caudal ray, this being in accordance with 

 Parneli's definition. 



The pectoral fin is placed proportionally rather further back in the 

 young herring than is the case in the sprat, and the centre of the dorsal 

 is generally slightly behind the centre of the body. 



The position of the dorsal fin varies much more in the sprat than in 

 the young herring, and I found the extremes of its position on the body 

 of the latter to lie within the extremes of its position in the sprat. The 

 reverse, however, occurs with the anal fin, that of the herring varying 

 more in its position, and the sprat's lying within the extreme points of 

 the situation of this fin in the herring. 



The following table of some of the measurements which I took shows 

 the extremes of variation which were found to occur in sprats of 

 114 mm. (4 J inches) in length (including caudal rays), and in herrings 

 of the same size. The position and length of fins, &c, given in the 

 table are taken from the measurements of several fish ; the minimum 

 length of head for instance, in a sprat 114 mm. long, not, in fact, being 

 found in conjunction with the minimum distance of the pectoral or other 

 fins from the premaxillse. 



