FRESH-WATER FISHES OF SIAM, OR THAILAND 551 



Genus CRYPTOCENTRUS Ehrenberg 



Cryptocentrus Ehrenberg, in Cuvier and Valenciennes, Histoire naturelle des 

 poissons, vol. 12, p. Ill, 1837. (Type, Cryptocentrus meleagris Ehrenberg.) 



Although the generic name Cryptocentrus (hidden spine) has no 

 significance when applied to these gobies, they constitute a fairly 

 well-marked group with six local species, two from the Menam Chao 

 Phya at Bangkok, two from estuarine waters of Southeastern Thai- 

 land, and two from rocky islets in the Gulf of Siam. All of these 

 are herein listed in order that the genus may be fully covered, al- 

 though some of them are outside the strict scope of this work. All 

 the local forms are of large size, compared with most gobies; that is, 

 they are 10 to 17 cm. or more in length, and all are of striking 

 coloration. 



Superficial resemblance to Oxyurichthys is marked. An outstand- 

 ing point of difference is the presence of teeth in the upper jaw in a 

 single row in OxyuricMliys and in several rows in Cryptocentrus. 



The species of Gryptoceni7ms included in this catalog have the fol- 

 lowing differentiating characters : 



la. Dorsal rays VI-1, 10 or 11 ; anal rays I, 9 or 10. 

 2a. Scales in longitudinal series about 75 to 95. 



3a. Caudal fin rounded ; body with dark cross bands, of which the 6 posterior 

 are most distinct ; dorsal rays with dark spots ; caudal with 10 trans- 

 verse lines of dark spots ; anal with about 10 dark bent bars ; veutrals 

 dark, with white spots ; pectorals with 6 transverse dark bands. 



maudae 

 3&. Caudal fin bluntly pointed. 



4a. Anterior dorsal spines not produced and shorter than head ; predorsal 

 region medianly scaled ; body pale brown, with 6 dark brown saddles ; 

 5 oblique dark stripes on side of head behind eye; anal fin with 4 

 dark longitudinal lines, the outermost forming an edge to the fin ; 



ventrais dark gray, other fins plain wehrlei 



4&. Anterior dorsal spines produced and longer than head in both sexes; 

 predorsal region medianly unsealed ; body pale buff, with 8 to 10 

 dark green or brown vertical or somewhat oblique cross bands ex- 

 tending entire depth of body; a large round dark spot on caudal 

 I)eduncle; first dorsal fin mostly pale brown, distal part of first 4 

 membranes pale orange, a large ocellus involving distal part of fourth 

 and fifth membranes and fifth spine consisting of a circular jet-black 

 center and a broad white and blue margin ; second dorsal fin with a 

 longitudinal median row of orange spots surrounded by pale yellow ; 

 anal fin with a brown margin and a brown longitudinal line near 

 base ; caudal fin with pastel tints of brown, blue, and yellow in length- 

 wise bands ; ventrais purplish black ; pectorals hyaline- callopterus 

 26. Scales in longitudinal series over 100 ; all scales cycloid ; caudal fin bluntly 

 pointed. 

 5a. Scales in longitudinal series about 125 ; body reddish brown, unmarked ; 

 head with 8 oblique dark stripes on cheek and opercle; fins mostly 

 plain, anal with 3 dark longitudinal lines leonis 



