igoQ.] N. Annandale : Report on the Batoidei. 53 



No. 



Breadth of teeth of 



jaw. 



upper 



Number of small teeth. 



Measurements of central tooth. 





Left. 



Right. 



Breadth. 



Length. 



ri* 



19-5 mm. 





3 



3 



T2"5 mm. 



1-5 mm. 



12* 



i8-o „ 





4 



3 



11-25 ,, 



2-0 ,, 



13 



21-0 ,, 





2 



2 



17-0 ,, 



; 3-0 ,, 



14 



20-0 ,, 





3 



' 



i6-o ,, 



175 M 



The numbers marked with a * refer to the specimens of the variety cornifera , the 

 remainder to those of the typical form of the species. 



The measurements printed above show how httle rehance can be placed on exact 

 relative proportions in diagnosing the species of the Myliobatidœ. Palaeontologists 

 in particular have attempted to separate the species of Myliobatis and even Aëtobatis 

 by examining the relative length and breadth of the teeth. Of one species only (M. 

 nieuhofii) have I been able to examine a .series of adult teeth. The measurements 

 speak for themselves. So far as the other Indian representatives of the family are 

 concerned, most of the jaws I have examined have been those of immature specimens. 

 So far as evidence founded on such specimens goes, however, there is every indica- 

 tion that variation is no less wide in the allies of M. nieuhofii than it is in that 

 species. 



Myliobatis maculata, Gray and Hardwick. 



This species may be distinguished from M. nieuhofii by (i) its large size, (2) 

 its coloration, (3) the arrangement and nature of its denticles, and (4) the shape of 

 the snout, 

 (i) The size of the adult appears to be nearly twice that of the adult of M. nieuhofii. 



(2) The young (which are often as large as the adult of the other species) have the 



dorsal surface of a deep bronze or greenish grey colour with rather large bluish 

 spots scattered profusely on the posterior part of the disk. These spots are a sign 

 of immaturity, although exactly the contrary is the case as regards Aëtobatis punc- 

 tata. The adult M. maculata has the back of a uniform dark slate-grey. 



(3) The most conspicuous feature of the scaling in this species is a longitudinal band, 



consisting of several closely adjacent rows, of flat denticles situated on the mid-Hne 

 of the scapular region. The small star-shaped denticles in the skin of the back 

 are also as a rule better developed in M. maculata than in M. nieuhofii. 



(4) The snout in M. maculata appears to be decidedly more prominent than it is in 



M. nieuhofii, but this is largely due to the fact that its sides form a more acute 

 angle. 



I have seen comparativel}' few fresh specnnens of this species, and onty one that 

 appeared to be an adult. It was taken by the ' ' Golden Crown ' ' off the Orissa coast, 



