chap, xi.] pilchard: scales. 275 



noticed. This was the case with the present specimens, which 

 were given to me as they came salted from the presses. Never- 

 theless when received they were in fairly good condition. 



The first specimen measured 8 in. to the base of the caudal fin. 

 The head and opercula were normal on both sides. The number of 

 scales along the lateral line or the left side is 32 and the number on 

 the right side is 56 or 57. On the left side the scales have the 

 size usually seen in Pilchards of this length, and on the right side 

 for a distance of about an inch behind the operculum the scales 

 are not much smaller than those of a normal Pilchard, but behind 

 this point each scale is of about half the normal size. 



The second specimen has a very similar length. It differs 

 from the first in having the reduplication on the left side in- 

 stead of on the right. Furthermore the scales are normal in 

 size as far as the level of the anterior end of the dorsal fin, behind 

 which place they are of about half the normal size. The transi- 

 tion in this specimen is quite abrupt. The scales had been 

 somewhat rubbed, and the counting could not be very accurately 

 made, but the total number along the left lateral line was 

 approximately 48. 



As these abnormal individuals were taken with the shoal there 

 can be little doubt that they were swimming with it. 



In P. Z. S., 1887, p. 129, PI. xv. Day described a specimen, also 

 obtained from Mr Dunn, exhibiting characters similar to those above 

 described. The number of scales along the lateral line is given as 32 

 on the right side and 51 on the left. In the ligure no transition from 

 normal to abnormal scales is shewn, but there is a general appearance 

 of uniformity. 



Mr Day regarded this specimen as a hybrid between the Herring 

 (C. liarengus) and the Pilchard, and before adopting the view that the 

 case is one of Variation this suggestion must be discussed. This view 

 was chiefly based on the presence of the small scales on one side, but it 

 is added that the ridges on the operculum, which are characteristic of 

 the Pilchard as compared with the Herring, were better marked on 

 the right side than on the left, though they are stated to have been 

 very distinct on the left side also. In the specimen described, the 

 gill-rakers were 61 in the "lower branch of the outer branchial arch" 

 (viz. the bar consisting of the first hypobranchial and ceratobranchial), 

 and it is mentioned that this number is intermediate between that 

 found in a Pilchard (71) and in a Herring (48) ; but whether this 

 intermediate number was found on the side shewing the "Herring" 

 characters, or on the other, or on both, is not stated. These gill-rakers 

 are also said to have been intermediate in length between those of a 

 Pilchard and those of a Herring. From these points of structure 

 Mr Day concludes that the specimen was a hybrid between the Herring 

 and the Pilchard. 



As against the theory that these specimens are hybrids it may be 

 remarked that no direct evidence is adduced which points to hybrid 

 parentage. The suggestion is derived from (1) the condition of the 



18—2 



