FRESH- WATER FISHES OF SI AM, OR THAILAND 301 



COBITOPHIS ANGUILLARIS (Vaillant) 



Acanthophthalmtis anguillaris Vaillant, 1902, p. 151 (Kapoeas, Borneo). — 

 FowLEE, 1934a, p. 103 (Chiengmai), 



Previously known only from Borneo, this species was first detected 

 in Thailand in July 1928 when a specimen was taken in a ditch near 

 the town of Chantabun, Southeastern region. In September 1932 

 it was found in Bung Borapet, Central area, and in December 1932 

 numerous specimens were collected in the Meping at Chiengmai, 

 Northern Thailand. 



The largest examples exceed 9 cm. in length ; the average is about 

 7 cm. The bifid suborbital spine is sharp and comparatively large. 



The fish is very numerous in Bung Borapet and in the Meping in 

 the vicinity of Chiengmai. Examples from Bung Borapet taken to 

 Bangkok were kept alive for months in a small jar of water. In a 

 thin layer of sand and gravel they completely disappeared and were 

 not observable unless disturbed, when they would swim about very 

 actively for a few moments with a wriggling motion and again 

 quickly bury out of sight. The skin is slippery like that of an eel, 

 and when the fish were put in alcohol a large amount of mucus was 

 precipitated. The fish was not fed but remained in good condition 

 apparently from the ingestion of minute animal or plant life in 

 water and sand. 



The respiratory movements are peculiar. In a vessel with no bot- 

 tom material in which the fish could hide, the movement of the gill 

 covers could be observed. This movement was sometimes so rapid 

 and strong that the entire head quivered. At other times, when the 

 fish were undisturbed and resting quietly with the head on gravel, 

 respiration would be suspended for 5 to 10 seconds, then resumed 

 with 5 to 15 movements, then suspended again, the pectoral fins all 

 the time remaining motionless and closely applied to the abdomen. 



Color in life : Back and top of head varying from pale bluish gray 

 to pale reddish brown with minute blackish spots ; a narrow sharply 

 defined black stripe along the side of the body, extending on head 

 to eye and snout and on median caudal rays where it spreads like a 

 fan ; side pale blue without minute spots ; belly pinkish white ; iris 

 orange; a glistening golden-green area on opercle; dorsal pale yel- 

 low, with black on the rays ; anal and other fins hyaline. 



Specimens from Northern Thailand showed differences from 

 Vaillant's figure (as reproduced by Weber and de Beaufort, 1916) as 

 regards the relative position of the dorsal and anal fins, and suggested 

 possible agreement with Acanthopthalmus vermicularis of Weber and 

 de Beaufort from Sumatra, a species based largely on the position of 

 those fins. The U. S. National Museum therefore donated specimens 

 from the Meping to the Royal Museum of Natural History in Leiden, 



