238 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



3a. Each scale of back and of side as low as ventral fin with a conspicuous 

 dark basal crescentic spot ; rostral tubercles in 2 rows ; mouth 0.5 

 width of head; length of caudal peduncle 1.5 times its depth; origin 

 of dorsal fin far in advance of ventrals, over eighth scale of lateral 



line melanotaenia 



36. Each scale of back and side without a dark basal spot ; rostral tubercles 

 in 4 rows divided into 2 series by a transver.se groove ; mouth as wide 

 as head ; length of caudal peduncle 2 times its depth ; dorsal fin well 



in advance of ventral, over tenth .scale of lateral line nigrovittatus 



2c. Multiple dark longitudinal stripes on back and side; pectoral fins equal to 

 or less than head. 

 4a. Four dark longitudinal stripes on p(»sterior half of body. 



5(1. Each scale of back with a blackish basal pocket ; head rather small, 4.4 



to 5.4 in length ; 4 series of rostral tubercles not divided by a deep 



horizontal groove; least depth of caudal peduncle much more than 



0.5 its length and much more than 0.5 length of head- quadrilineatus 



5&. Each scale of back and side without a dark basal pocket ; an elongate 



black blotch at posterior end of lateral line extending ou median 



caudal rays ; head larger, 4 in length ; 4 series of i-ostral tubercles 



divided into 2 parts by a deep horizontal groove; least depth of 



caudal peduncle 1.5 in its length and 0.5 length of head— trangensis 



4&. Five or 6 dark longitudinal stripes on posterior two-thirds of body ; 



head 4 to 4.3 in length ; 4 series of large rostral tubercles divided into 



2 parts by a deep horizontal groove; least depth of caudal peduncle 



0.5 its length and 0.5 length of head cornutus 



4c. Eight or 9 dark, not sharply defined, longitudinal lines following rows of 



scales on back and side. 



6a. Anterior margin of dorsal fin black; free edge of dorsal fin with a 



narrow, sharply defined black border; 2 short, diffuse dark gi-ay 



cross bars on caudal peduncle near base of caudal fin ; least depth 



of caudal peduncle 1.4 in head cryptopogon 



66. Anterior margin and free edge of dorsal fin not black; a dark line 

 along body axis terminating in an elongate black blotch on caudal 



peduncle; caudal peduncle about length of head davlsi 



16. Body more elongate, depth 4.2 to 5 in standard length. 



7a. Body marked by a single more or less complete dark longitudinal band or 



stripe. 



8a. A dark longitudinal stripe on posterior half of body terminating in a 



small round spot on caudal peduncle; a dark median dorsal streak; 



dorsal fin pale ; origin of dorsal fin over base of ventrals ; depth 4.2 



to 4.5; head 3.3 to 3.5; gill rakers about 5+28; scales in transverse 



series 6 or 7-1-3 rhabdoura 



86. A jet-black longitudinal band from head to posterior end of middle 

 caudal rays ; no dark median dorsal streak ; dor.sal fin with its anterior 

 margin black and its membranes mostly blackish ; origin of dorsal fin 

 in advance of ventrals; depth 4.5; head 4.3; gill rakers 5-f22; scales 



in transverse series 5.5-1-3 cheveyi 



76. Body marked with multiple dark longitudinal lines. 



9a. Three dark longitudinal stripes on posterior part of body; dorsal, anal, 

 ventral, and pectoral fins falcate ; depth 4.5 to 4.75 ; head 3.8 to 4.2. 



gracilis 



96. Nine dark longitudinal stripes extending entire length of body, one on each 



side of lateral line most distinct ; a large dark spot on caudal peduncle 



near base of caudal fin ; fins not falcate, depth 5 ; head 5 thavili 



