44 The Cartilaginous Fislies of Lower Bengál. [No. 1, 



on the tail are less conspicuous and dístinct than in Te. Russellii. 

 In stuífed specimens the markings are apt to disappear totally ; and 

 it is as well, therefore, to preserve a portion of the fresh skin of this 

 and other species in spirit. 



23. Te. uaenak, (Forsk.) Young figured in Rüppell's Neue 

 Wirbelthiere. Much like Te. Russellii, but not attaining (I suspect) 

 to nearly so great a size ; the dorsal surface speckled with numerous 

 small spots (as in Rüppell's figure). The teeth also are considerably 

 smaller than in Te. Russellii in specimens of corresponding size. 

 In an example less than a foot in length (ininus the tail), or of a size 

 at which Te. Russellii has few and sparse tubercles on the back 

 and a single row only of curved tubercles at base of tail (as shewn 

 in Hardwicke's figure ), Te. uaenak has the dorsal tubercles fully 

 developed, and a broader band of them at base of tail than is seen 

 in Te. Russellii of more than double the size, — whence I conclude 

 that it is a much smaller species when full-grown, and that the 

 tubercles probably surround the base of tail in adults, as in Te. 

 vaeiegatus. I have only once obtained it ; and the specimen has a 

 single large tubercle on centre of back, and three slightly larger than 

 the rest placed in a triangle behind the principal tubercle.* 



Of these various long-tailed Trygons I have seen no intermedíate 

 specimens ; and in the fresh state they may be recognised at a glance 

 by the colouring, which unfortunately disappears more or less com- 

 pletely in dry museum specimens, The only species which I have 

 obtained with the caudal spine are the small Te. imbeicatus and 

 Te. walga, Hypolopuus sephen (small), and Aütobatis ela- 

 GELLUM (small) ; and I am not aware that any difference occurs in 

 the structure of that formidable weapon in the different species 

 here noticed. 



While preparing this paper, I have (in the course of a few weeks) 

 obtained fresh examples in the Calcutta fish-bazars of Teygon mae- 



* I have since obtained another, not very much smaller, in which the tail is 

 quite naked. Two examples of Te. Russellii were procured on the same occasion ; 

 and the peak is more obtuse in Te. uaenak than in Te. Russellii ; as seen in 

 fresh specimens, — the dry being very much subject to be stretched out of the 

 proper shape. Dr. Bleeker gives the breadth of Te. uaenak (fsein.) as 240 et 315 

 mili. Virh. Bat. Gen.¡ Yol. XXIV, (1852) ; but then he considers Te. Russellii 

 to be identical with it. 



