CATFISH GENTJS NOTURUS RAFINESQUE 



Figure 1. — Chart showing, by sex and size, the number of caucdal rays in Noturus miurus. 

 All specimens are from an area 2 or 3 miles northwest of Dexter, Michigan. Those collected 

 in August were young that had not left the nest (see p. 30). Specimens above 20 mm., which 

 were collected in the spring, had a full complement of caudal rays. No sexual difference 

 in number of rays is evident. In the yearlings and older specimens the rays are distinct 

 and stand out from the surrounding tissue. In the young, counts were made after staining 

 with alizarin red S. Without this preparation the rays graded imperceptibly into the 

 primordial fin tissue. 



Upper-half caudal rays: Approximately one-half of the caudal fin 

 is above a rather broad gap between the rays that extend from beneath 

 the end of the axial streak (the line formed by the junction of the 

 epaxial and hypaxial muscles). This displacement of the rays, near 

 the middle of the fin, results from their attachment above and below 

 a wide gap between the three lower and three or four upper hypurals. 

 All rays, both simple and branched, that are above this gap are 

 included in the upper half of the fin. 



Lower-half caudal rays: All rays below the above mentioned gap . 



Total caudal rays: All rays in the caudal fin. 



Branched rays in the upper half of the caudal fin (upper lobe rays) : 

 All branched rays in the upper half of the fin. 



Branched rays in the lower half of the caudal fin (lower lobe rays) : 

 All branched rays in the lower half of the fin. 



Caudal fin-ray data where indicated in descriptions, include in 

 order: upper simple rays, upper lobe branched rays, lower lobe 

 branched rays, and lower simple rays, equaling total caudal rays. 



