76 MADRAS FISHERIES BULLETIN VOL. XV, 



Inclusion of the caudal fin also has the advantage of bring- 

 ing the resulting proportions in line with those of earlier writers, 

 and a proportion based on the newer method makes comparison 

 practically impossible. I believe we can afford to waive a nice 

 morphological point in favour of practicability, so long as the end 

 in view does not suffer. 



2. Length of head.— The length of the head has been measured 

 by placing the snout of the fish in contact with a vertical surface, 

 and, by means of dividers, measuring the distance from the vertical 

 to the posterior edge of the operculum. 



3- Snout. — Similarly for the snout, the measurement has been 

 taken from the vertical mentioned to the front edge of the orbit by 

 means of dividers. 



4. The eye. — In general, the diameter of the eye is easily measured 

 with dividers ; but where thick, and, after immersion in spirit, 

 rather opaque, lids are present, there arises some difficulty. In 

 some cases, I have found it necessary even to remove the eyelid 

 before taking the measurement. 



5. Interorbital space. — The distance between the dorsal edges of 

 both orbits has been measured directly by dividers. 



6. Mandibular angle. --Angles varying from 105 to Il8 degrees 

 were cut from cardboard in order to measure the angle between the 

 rami of the lower jaw. An angle from HO to 112 degrees, being 

 the commonest met with, was regarded as " normal " ; if below 

 this figure, the angle is described as " acute," clearly using this term 

 not in the strict mathematical sense, but only in comparison with 

 the normal. Similarly, when the angle exceeded 1 12 degrees, it is 

 spoken of as " obtuse." I fully appreciate the possible objections 

 to this misuse of terms, but hope to justify it on practical grounds; 

 this angle, in all the mullets I have examined, was, strictly speaking, 

 obtuse, hence the difficulty in conveying the degree of obtuseness 

 without circumlocution ; figures are of little use unless a measuring 

 gauge is employed. It may be noted that those which I have called 

 acute do, in general appearance, appear in comparison with the 

 normal to be practically a right angle ; measurement proved them 

 to be greater, but I am inclined to think that those which Giinther 

 described as a right angle were probably actually greater. 



7. Height of body. — The greatest height, or depth, of the body was 

 measured directly by means of dividers ; it should be remembered 

 that varying degrees of fiaccidity or distention of the body does 

 affect this proportion. 



