1410 Catalogue of Malayan Fishes. [Dec. 



to the anus, is less than one half of the breadth of the disk, or the distance 

 between the external angles of the pectorals. In older individuals the 

 length is f of the breadth of the disk. The distance between the inner 

 angles of the nostrils is about one half of the greatest diameter of the 

 nostril. The distance between the external angles of the nostrils is double 

 the distance from their centre to the point of the snout, or their nearest 

 distance from the pectoral margin. The teeth are tricuspidate ; their cen- 

 tral cusps are erect and longer than the lateral horizontal ones. In both 

 jaws the teeth are confined to the central third, on each side of which 

 in the upper jaw appears a notch corresponding to a minute prominence 

 in the lower jaw. The depressed tongue occupies the whole breadth 

 of the mouth. The margin of the spiracles carries no denticle. The body 

 is naked. The ventral fins are elongated tetragonal, with the posterior 

 angles rounded. The male appendages project beyond the inner margins 

 of the ventrals, and extend to the root of the caudal spine. The length 

 of the tail varies : in the very young it is shorter than the body, later 

 it becomes a little longer than the body. It is depressed towards the 

 spine, from thence it is cylindrical, very slender and tapering. It has 

 no fins. The slender spine is situated at the anterior fifth. In the 

 young, with the disk upwards of one foot in breadth, it is hidden in 

 the integuments, and scarcely y 1 ^ of the length of the tail. In a male, 

 15f inch in breadth, the spine is nearly ^ of the length of the tail. 

 The largest individual observed was taken in 1840 near the Island of 

 Lantao, in the mouth of the Canton River ; the disk measured 4 feet 

 in breadth, 3 feet in length, and the tail 1 foot. The tail was armed 

 with two spines situated close to each other ; each about one inch in 

 length. Single young individuals occur at all seasons in the Straits of 

 Malacca. 



Dimensions. 



From the snout to the mouth, If inch. 



From the mouth to the anus, 4f 



Length of the tail, 8 



Distance between the inner angles of the nostrils, Of 



Greatest diameter of the nostrils, Of 



From the snout to the eyes, Of 



Distance between the eyes, If 



Breadth of the disk, 154 



