92 



Appendices to Fourth Anmuxl Report 



The uumber of rays in the pectoral fin varies from 15 to 19 ; the per- 



centages beino- — 



With 15 rays, 

 » 16 „ 

 » 17 „ 

 JJ 18 J) 

 , 19 „ 



•9 per cent. 

 17-6 „ 

 56*0 „ 

 22-7 „ 



_2^ » 



100-0 



There seems to be a slight tendency towards an increase in the number 

 of fin rays (always excepting those of the pelvic and caudal fins) as the 

 herring grows larger, for there is seldom an immature herring found with 

 the higher number of rays nor a large fish with the lower, which seems to 

 be due to the fact that in the immature and younger fish, that which will 

 eventually become the first ray is so small as readily to escape notice, often 

 indeed being hidden by the scales. 



The caudal fin consists of 19 rays, excluding the small imperfect rays 

 on the external part of the root of the fin, and counting only the two 

 unsplit rays which form the dorsal and ventral edge of the fin proper and 

 the rays included between them. These caudal-fin rays are not equally 

 distributed between the upper and lower lobes of the fin. There is no 

 median ray, and the real centre line of the fin * is formed by the space- 

 rather wider than 

 eleventh rays. 



lower. This is true for 



between the others — lying between the tenth and 



lobe and 9 in the 

 The variations to 



there being thus 



10 rays in the upper 

 the winter and summer fish. 





With 



11 





JJ 



10 





5J 



9 





3> 



9 



9 in lowe 

 9 



r, -3 per cent. 

 98-0 „ 



9 

 8 





•85 „ 

 •85 „ 





Keeled Scales. 



My observations on the number of these are as yet too few to afford 



So far as I 



a 



have 



fair comparison bet^ween the summer and winter fish 

 gone I have not been able to detect such a difference between the respec- 

 tive numbers of these as Heincke has done in the Baltic herring, and which 

 enables him to quote them as a racial distinction. 



These scales may be divided into three sets — partly from their difference 

 in form, partly from their position. At the anterior end of the body of 

 the herring is a series of small, narrow, oval-shaped scales, with only a 

 slight keel, and no diverging rays. These form the first set. Behind 

 these small scales come the ordinary keeled scales, all provided with the 

 diverging rays which pass a short way up the sides of the abdomen. 

 These scales are continuous as far back as the vent, and may be divided 

 into those anterior and those posterior to the pelvic fin, the last scale of 

 the former set having two or three modified rays, apparently the result of 

 the combination of more than one scale. The total number of the three 

 sets varied froni 41 to 46 in the herrings examined, 



cent, of the herrings having 41 scales. 



42 „ 



JJ » 43 ,, 



44 



JJ j> JJ 



JJ JJ 45 



46 



JJ JJ ^ JJ 



The average number being 42-5. 

 * Looking at the external symmetrical condition of the fin and disregarding the 

 arrangement of the rays with respect to the urostylar bone. 



14-3 





per 



42^7 



JJ 



25-7 



>j 



11-4 



JJ 



2-9 



JJ 



2-9 



> J 



