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a. absent (Fig. 47) .......... C. discobo/us b. present (Figs. 32, 46) ............. 131 131 (130). Pigment in pectoral fin a. absent or present but very light with ::510 melanophores (Fig. 47) ........... 132 b. present but more prominent with ~11 melanophores (Fig. 61) ... C. commersoni 132 (131). Number of myomeres to posterior margin of vent a. 34 .................. C. commersoni b. 35-40 . . . . . . . . . . . . . . . . . . . . . . . .. 133 133 (121,132). Total number of myomeres a. 43-46 . . . . . . . . . . . . . . . . . C. commersoni b. 47-49 . . . . . . . . . . . . . . . . . . . . . . . .. 134 134 (133). Dorsal body pigmentation between head and last myomere scattered a. more or less evenly (with or without emphasis on distinct lines of melano- phores on or lateral and parallel to dorsal midline) (Fig. 47) . . . . . . . . . .. 135 b. but in a blotchy pattern (with or without emphasis on distinct lines of melano- phores on or lateral and parallel to dorsal midline) (Fig. 48, 49) . C. discobolus 135 (134). Pigment in dorsal fm a. along fm rays with very few, if any, melanophores on membrane between rays (Fig. 47) ................... 136 b. abundant both along and between rays (Fig. 33) .............. C. commersoni 136 (135). Pigment in anal fm a. absent or fin present but very light with only a few (:$5) melanophores (Fig. 47) .......................... 137 b. present but more prominent with many (~6) melanophores (Fig. 61) C. commersoni 137 (136). Length from anterior margin of snout to origin of pelvic fm a. 54% SL . . . . . . . . . . . . . . . C. commersoni b. 55-59% SL . . . . . . . . . . . . . C. commersoni C. discobolus c. 60-61% SL . . . . . . . . . . . . . . C. discobolus 138 (64,66). Longitudinal eye diameter a. 22-25% of head length ...... C. latipinnis b. 28-33% of head length ........ C. arde1lS 139 (71,90). Longitudinal eye diameter a. 24-27% of head length . Xyrauchen texanus b. 28-32% of head length ... ..~ . . . . .. 140 c. 33% of head length .. . . . ... . . . C. ardens 140 (139). Length of base of dorsal fm (origin to insertion of dorsal fm) a. 14-15% SL . . . . . . . . . . . . . . . . . C. ardens b. 16% SL . . . . . . . . . . . . . . . . . . . . . .. 141 c. 17-21% SL . . . . . . . . . . . . . . . . X. texanus 141 (140). Dorsal fin length a. 18-20% SL ................ C. ardens b. 21-29% SL ............... X. texanus Skeletal Character Key for Metalarvae that have been cleared and preferably stained for bone or cartilage (Fig. 6). 1. Standard length group (Fig. 4) a. ::516 mm ........................ 2 b. 17-18 mm ....................... 3 c. 19-21 mm ....................... 5 d. ~ mm ........................ 9 2 (1). Number of vertebrae (including 4 for Weberian complex) a. 42-43................ C. platyrhynchus b. 44 . . . . . . . . . . . . . . . . . C. commersoni C. platyrhynchus c. 45-46 . . . . . . . . . . . . . . . . . C. commersoni C. discobo/us C. platyrhynchus X. texanus d. 47 . . . . . . . . . . . . . . . . . . . . . C. ardens C. commersoni C. discobo/us C. platyrhynchus X. texanus e. 48 . . . . . . . . . . . . . . . . . . . . . C. ardens C. commersoni C. discobo/us C. platyrhynchus f. 49-50.................. C. discobolus (rarely) C. platyrhynchus 3 (1). First (most anterior) interneural bone (Fig. 8) a. large and fan-shaped across top X. lexanus b. large and angular or anvil-shaped with a prominent posterior-directed projec- tion or beak . . . . . . . . . . . . . . . . . . . . . . 4 c. small and blocky or angular with a small to moderate posterior-directed projec- tion or beak. . . . . . . . . . . . . . . . . . . .. 11 4 (3). Number of vertebrae (including 4 for Weberian complex) a. 44-46 . . . . . . . . . . . . . . . . . C. commersoni b. 47-48 . . . . . . . . . . . . . . . . . . . . . C. ardens C. commersoni 5 (1). Frontoparietal fontanelle (Fig. 7) a. wide,::554% of fontanelle length ....... 6 b. very wide, 55-64% of fontanelle length (often somewhat oval in shape) ....... 8 c. very wide, ~65% of fontanelle length (often somewhat oval in shape) X. texanus 6 (5). rust (most anterior) interneural bone (Fig. 8) a. large and angular or anvil-shaped with a prominent posterior-directed projec- tion or beak . . . . . . . . . . . . . . . . . . . . . . 7 b. small and blocky or angular with a small to moderate posterior-directed projec- tion or beak .. . .. .. . .. .. . .. .. .... 11 81