80 MADRAS FISHERIES BULLETIN VOL. XV, 



found in which it originates above the 10th, but if the 21st scale 

 is normal for the origin of the second dorsal fin, cases will be found 

 where a count will show the origin to be above, say, the 23rd. 



By dropping a vertical line from the origin of the second dor- 

 al fin across the tail to the base of the anal fin, the "advance" of 

 the anal before the second dorsal is determined ; the origin of 

 both may be in the same vertical line — in other words opposite one 

 another ; or the anal may have a fraction of the length of its base 

 in advance of the dorsal. This is a reliable character, and one in 

 which little variation occurs. 



2. Proportions. — For a group like the mullets, where the several 

 species so closely resemble each other, the value of proportions is 

 of secondary importance. The range of variations causes much 

 overlapping in the proportions of the various species and several 

 species have almost identical proportions. Young specimens fre- 

 quently show different proportions from those of the adults ; they 

 also require the most exact measuring, since, in small measurements* 

 such as the length of the snout, or the diameter of the eye, the small- 

 est error makes a considerable difference in the resulting propor- 

 tions. For mullets, therefore, I can only recommend the use of some 

 proportions as corroborative evidence ; it is impossible to con- 

 sider them as of primary importance. 



3. Colour. — Bluish grey above and silvery below very well de- 

 scribes the general colour for all the grey mullets ; the differences in 

 colour are, in the main, differences in detail only. The presence of a 

 dark spot at the base of the pectoral fin is a most useful character; 

 dark tips to the median fins must be distinguished from a mere 

 darker edge to these fins, or the character is liable to become uni- 

 versal for mullets ; dark lines along the rows of scales in the upper 

 half of the body is often a useful character. However, striking 

 differences in colouration are not found among the mullets. 



DESCRIPTIONS OF THE SPECIES. 



MUGIL CEPHALOTUS Cuv. & Vol. 

 M. (vnr Forsk. and Day. 

 D. 4 I 1/8. A. 3/8. L. 1. 40-43. L. tr. 14. 

 This mullet, which attains considerable size, commonly 18 

 inches, is a common species in Tuticorin; it can be readily identi- 

 fied by the following features: — 



