FRESH-WATER FISHES OF SlAM, OR THAILAND 351 



and the anal rays 60 to 62, while in Fowler's example the dorsal rays 

 number about 70 and the anal rays about 50. The foregoing and other 

 characters in which the Bangkok specimen differs specifically from 

 G. leiacanthus agree perfectly with G. tnacrocephalus Giinther (q. v.). 



CLARIAS MACROCEPHALUS Gunthcr 

 FiGUBE 79 



Clarias tnacrocephalus Gunther, 1864, vol. 5, p. 18 (Siam). — Sauvage, 1881, p. 161 



(Siam).— Smith, 1934b, p. 291 (Siam generally). 

 Clarias liacanthus Fowler, 1934a, p. 87 (Bangkok) (nee C. leiacanthus Bleeker). 



This species was described from Thailand from four adult and half- 

 grown specimens in the British Museum acquired in the Jamrach pur- 

 chase. It is now known also from French Indo-China and the 

 Philippines. 



Its length may exceed 31 cm. 



Figure 79. — Clarias macrocephalus Giinther. Drawn by Nai Chote Suvatti; courtesy of 



the Thailand Government. 



This form is readily recognizable by its large head; broad, low, 

 evenly curved occipital process extending close to the dorsal fin ; nasal 

 barbels reaching to or beyond the gill openings; maxillary barbels 

 extending to the middle or tip of the pectorals ; vomero-palatine teeth 

 obtusely conical, forming a crescent-shaped band, which in its center 

 is broader than the intermaxillary band ; and a nearly smooth pectoral 

 spine. 



Giinther's description is sufficient to differentiate the species from 

 its nearest ally, G. leiacanthus^ although Weber and de Beaufort con- 

 sidered G. macrocephalus "a rather doubtful species." It does not ap- 

 pear to occur in the Indo-Australian Archipelago, and while Weber 

 reported it from Sumatra in 1894, his specimens were subsequently 

 adjudged to represent G. hatrachus. 



Dr. Frederik P. Koumans, of the Koyal Natural History Museum in 

 Leiden, Holland, courteously examined for me specimens of G. macro- 

 cephalus from three localities in Central Thailand and compared them 

 with Bleeker's cotypes of G. leiacanthus. He found the species closely 

 allied but disclosed differences that have already been indicated and 

 others, such as the size of the eye (larger in G. macrocephalus) , length 



