32 U.S. NATIONAL MUSEUM BULLETIN 2 82 



(mean 12.8 mm.) in standard length. The body form is like that of 

 the adult; the yolk sac has degenerated and pigmentation is well 

 advanced. The full complement of soft dorsal, soft pectoral, and 

 pelvic rays is present (i.e., 6, 8, and 9 in each fin, respectively). There 

 are nine branchiostegal rays in several. The anterior pectoral-spine 

 serrae are present; there are two posterior serrae on each side in all 

 specimens. The pectoral radials are ossified and distinct with one 

 exception; those of the left side of an individual 12.8 mm. long have 

 the ends fused. 



The skuU is poorly ossified. There are no definite bones in the 

 infraorbital canal system or along the lateral line. The supraorbital, 

 lateral, and preoperculomandibular canals are encased in tubes of 

 bone that almost exceed in diameter the remainder of the bony ele- 

 ments through which the canals pass. The humeral process is long; 

 the maxilla is scarcely visible. 



Even at these sizes, the anal fin is virtually complete and the 

 caudal fin has over 80 percent of its rays present (i.e., that take up 

 the alizarin stain) . The middle rays of the fin are beginning to branch. 

 The following summary gives the range and mean for data from: 



(a) the first group, averaging 12.5 mm. in standard length, (b) the 

 second averaging 12.8 mm., and (c) large specimens and adults 

 from the same locality. Upper-half caudal rays: (a) 26-28 (27.1), 



(b) 23-29 (27.1), (c) 30-35 (32.5). Lower-half caudal rays: (a) 22-24 

 (23.0), (b) 20-24 (22.7), (c) 24-29 (26.4). Total caudal rays (fig. 1): 

 (a) 49-52 (50.1), (b) 43-53 (49.8), (c) 55-64 (58.9). Anal rays: (a) 

 14-15 (14.6), (b) 14-16 (15.1), (c) 14-17 (15.2). 



Subgenus Schilbeodes Bleeker 



Schilbeodes contains all of the dark, nearly uniform colored species 

 of Noturus except flavus. The nine included species show a diversity 

 of characters that precludes an adequate phylogenetic arrangement 

 of the species and may indicate that this grouping is polyphyletic. 



In addition to the dark color pattern, there are usually 8 or 9 pelvic 

 rays, 6 to 10 soft pectoral rays, and 10 or 11 preoperculomandibular 

 pores. The pectoral spine (pi. 3, figs. 1-9) varies from short and blunt 

 to long and relatively straight; it is deeply grooved in A^. gyrinus to 

 very shallowly grooved in A'', leptacanthus ; there are no anterior 

 serrae, but the anterior edge may have recurved hooks or step-like 

 processes; the posterior edge is variably serrate or smooth; the devel- 

 oped serrae are of variable shape or nearly straight, their tips never 

 uniformly turned toward spine base; the mouth is terminal or inferior; 

 the premaxUlary tooth patch is a short, rectangular band without 

 prominent posterior projections. The branchiostegal rays vary from 

 8 to 12; vertebrae anterior to the first pterygiophore of the anal fin 



