Zoology.-] NATURAL HISTORY OF VICTORIA. [Fishes. 



Plate 63. 



MYLXOBATIS AUSTRALIS (Macleay). 

 The Blue-spotted Eagle-Ray. 



[Genus MYLIOBATIS (Cuv.). (Sub-kingd. Vertebfata. Class Pisces. Order Plagios- 

 tomata. Sub-order Batoidei. Family Myliobatidse.) 



Gen. Char. — Head rounded, much elevated, with a flattened, rounded, fleshy expansion in 

 front, distinct from the disc, which is formed by the lateral development of the pectoral fins. 

 Nasal valves coalescing to form a broad, transverse, median, oblong flap, with a concave, fringed, 

 posterior margin. Mouth with rectilinear edges, the lower not extending in front of the upper. 

 Teeth hexagonal, flat, the middle row much wider than long, those of the lateral rows having the 

 length and width nearly equal. Tail long, slender, with a dorsal fin near its base, and a small 

 serrated spine behind the dorsal fin.* Eyes directed laterally, each with a very large spiracle 

 close behind it ; no upper eyelid.j 



Description. — Body : Smooth, rhomboidal ; pectoral fins moderately acute and 

 falcate at the tips ; anterior edge nearly straight, very slightly convex except near 

 the tip, posterior margin sigmoid, slightly convex near posterior acute angle, and 

 gently concave towards the apex ; anterior margin in front of head obtuse, semi- 

 elliptically rounded, the rounded angular junction with the anterior border of the 

 pectoral disc being in about a line connecting the middle of the eyes ; an obtuse 

 ridge over each orbit converging to back part of head, leaving a deep concave 

 median hollow. Disc from tip to tip of pectorals less than twice the, length to 

 posterior base of ventral fins, more nearly twice from anterior edge of snout to 

 posterior edge of pectoral fin. Ventrals subquadrate. Dorsal fin more than the 

 length of its base behind the posterior root of the ventrals, or its middle about over 

 the posterior edge of the ventrals. Spine a rather less distance behind the posterior 

 edge of dorsal. Tail beyond the spine suddenly reduced in diameter, forming a long 

 slender termination (imperfect in our specimen, and therefore its length cannot be 

 given). Teeth : Median teeth of upper jaw 7-J- times wider than long (or 7\ in a 

 space equal to the width of one) ; length and width of the lateral teeth nearly 

 equal. Color: Uniform yellowish olive-brown above, with about 26 or 28 large 

 light-blue rounded spots, irregular in shape and distribution, over the disc ; under- 

 side white in the centre, becoming pinkish-brown and yellowish towards the margins 

 of the pectoral. 



Measurements. 

 Length from anterior edge of snout to base of tail at posterior 

 root of ventrals ... ... ... ... 



Width from tip to tip of pectorals 

 Antero-posterior diameter of eyes 



„ „ spiracles ... 



Distance between the eyes 

 Rounded projection in front of head 

 From tip of snout to posterior base of pectorals ... 

 Width of posterior margin of ventrals 



* Dr. Giinther states that in young individuals the tail is much longer than in old ones, and that the median teeth 

 re regularly hexagonal and of the same size as the lateral ones. 



[ ii ] 



Ft. 



Ins. 



lines. 



r 



. 2 



5 







. 4 



1 







. 



1 



3 



. 



2 



3 



. 



5 



9 



. 



2 







. 2 



1 







. 



6 



6 



