396 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



attached itself indifferently to any surface — stone, glass, porcelain, 

 wood basket-work, or vegetation — and the sucking action of the lower 

 lip was supplemented by corrugations on the front and sides of the 

 head ; these corrugations becoming less distinct in preservative. 



The respiratory movements of the opercular flaps were rapid but 

 not very marked. As the fish faced the current, the long nasal barbels 

 were fully extended vertically and at their base the nostrils were con- 

 spicuous as triangular openings, the apex of which reached nearly half 

 the length of the barbels. There was no obvious current of water into 

 the mouth and out of the branchial openings ; possibly a feeble current 

 of water to the gills through the branchial openings was induced by 

 the movements of the gill flaps. 



This fish, which differs so strikingly from the other catfishes in 

 the mountain streams of Thailand, seems to be known to the moun- 

 tain people, who give the name 'pla tit hin (stone-sucking fish) to no 

 other fish. 



Genus GLYPTOTHORAX Blyth 



Glyptothorax Blyth, Jonrn. Asiatic Soc. Bengal, vol. 29, p. 154, 1860. (Type, 

 Glyptothorax trilineatus Blyth.) 



The Glyptothorax fishes are small inhabitants of mountain streams, 

 in which they are aided in maintaining themselves by means of a cor- 

 rugated thoracic disk, wdiich acts as an adhesive apparatus. Criteria 

 for specific determination are the length of body and of caudal pe- 

 duncle with reference to depth, the degrees of depression of the head 

 and the ratio of length to width, the length of the occipital process, the 

 length of the maxillary and nasal barbels, the shape of the thoracic 

 disk, the degree of granulation of the skin, the length of serrature of 

 the dorsal and pectoral spines, the origin of the ventral fins with ref- 

 erence to the dorsal, and the coloration. The numerous local species 

 may be identified by the following characters : 



lo. Origin of ventral fins approximately under last rays of dorsal fin. 

 2a. Body very slender, its depth (in Siamese specimens) contained 6 to 6.5 

 times in standard length; length of caudal peduncle 2 to 2.5 times its 



least depth platypogonoides 



26. Body less slender, its depth contained 4 to 5.5 times in standard length. 

 3a. Body dark brown, marked by sharply defined white longitudinal stripes 

 (one on midline of back from head to caudal fin, one along lateral line 

 from head to caudal fin, one on median ventral surface between ventral 

 and caudal fins) ; depth of body 4.6 to 5.5 times in standard length, 

 varying with age ; length of caudal peduncle 2.25 to 2.5 times its least 



depth trilineatus 



3&. Body not marked by white longitudinal stripes ; length of caudal 

 peduncle 1.3 to 2 times its least depth. 

 4a. Body with large blackish or dark brown blotches; depth of body 4.6 

 times in its length ; caudal fin much longer than head lampris 



