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Colorado -- Snyder 1981, Tyus et al. 1982). However, such data must be used cautiously. Positively identified fish larvae are often the basis for revision of previous assumptions regarding spawning seasons and grounds, lar- val drift or migration, nursery habitat, and sometimes species distribution. The authors appreciate notification of errors, misleading criteria, or problems uncovered by users, as well as suggestions for revisions. Eggs -. water hardened (embryos with pigment- ed eyes can be removed from the chorion and further identified using the key for protolarvae ). 1. Diameter (maximum) a. 2.3-2.4 mm . . . . . . . . . . . . C. platyrhYllchus b. 2.5 mm .............. C. platyrhynchus X. texanus c. 2.6-2.7 mm . . . . . . . . . . . . . C. commersolli C. platyrhYllchus X. texallus d. 2.8 mm ............... C. commersolli X. texanus e. 2.9-3.2 mm ................ C. ardens C. commersoni f. 3.3 mm ............... C. commersolli C. discobolus g. 3.4-3.6 mm ............. C. discobolus h. 3.7-3.9 mm .............. C. latipinnis Proto larvae -- no caudal fin rays (definition abbreviated for species of concern; Figs. 3, 4, 14, 15) 1. Standard (notochord) length (SL; Fig. 4) a. 7mm ..........................2 b. 8 mm .......................... 4 c. 9mm ..........................7 d. 10 mm . . . . . . . . . . . . . . . . . . . . . . . . . 12 e. 11 mm . . . . . . . . . . . . . . . . . . . . . . . . . 15 f.12mm.........................19 g. 13 mm . . . . . . . . . . . . . . . . . . . . . . . . . 21 2 (2). Eyes a. unpigmented ............... C. ardells C. commersolli C. platyrhYllchus X. texanus b. lightly to moderately pigmented (Figs. 70, 84) ......................... 3 3 (2). Body a. unpigmented (Fig. 84) ............ 129 b. sparsely pigmented, :$12 melanophores (spots of black or brown pigment) on dorsal surface (Fig. 70) . . . . C. commersolli 4 (1). Pectoral fm buds a. absent ................. C. discobolus C. latipillnis b. present (Figs. 70, 84; buds initially form as minute crescents high on anterior surface of yolk sac and are later above and anterior to yolk sac) . . . . . . . . . . . . . 5 5 (4). Eyes a. unpigmented ............... C. ardells C. discobolus C. platyrhYllchus X. texanus b. lightly to moderately pigmented (Figs. 70, 84) ....................... 142 c. darkly pigmented (Fig. 71) ........... 6 6 (5). Body a. unpigmented to sparsely pigmented, :$12 melanophores (spots of black or brown pigment) on dorsal surface (Fig. 70) '" 93 b. moderately to well pigmented, ~13 melanophores on dorsal surface (Fig. 71) . . . . . . . . . . . . . . . . . . . . . . . . . . 24 7 (1). Yolk a. present ......................... 8 b. absent . . . . . . . . . . . . . . . . . . . X. texanus 8 (7). Pectoral fm buds a. absent . . . . . . . . . . . . . . . . . . C. latipinnis b. present (Figs. 70, 84) initially form as minute crescents high on anterior sur- face of yolk sac and are later above and anterior to yolk sac) . . . . . . . . . . . . . . . . 9 9 (8). Eyes a. unpigmented ............... C. ardells C. commersolli C. discobolus C. latipillnis C. platyrhYllchus X. texanus b. lightly to moderately pigmented (Figs. 70, 84) ........................ 10 c. darkly pigmented (Figs. 71, 85) . . . . . .. 11 10 (9). Body a. unpigmented (Fig. 84) ............ 122 b. sparsely pigmented, :$12 melanophores (spots of black or brown pigment) on dorsal surface (Fig. 70) ........... 132 11 (9). Body a. unpigmented (Fig. 84) ............ 129 39