10 U.S. NATIONAL MUSEUM BULLETIN 282 



A synopsis of certain characters of the Ictaluridae follows: body 

 lacking scales but covered with thick skin; form moderately elongate; 

 branchiostegal membranes forming a fold across the isthmus; dorsal 

 fin anterior, with a hard spine (except Prietella) and usually with 

 six soft, segmented rays; adipose fin present and of variable length; 

 anterior and posterior nares relatively far apart; jaws toothed except 

 in Trogloglanis ; palate toothless; villiform teeth, similar to those of 

 the jaws, in small patches on upper and lower rear pharyngeal arches; 

 upper pharyngeal tooth patch obovate; lower pharyngeal arch S- 

 shaped and bearing a diamond-shaped patch of teeth; palatine rod- 

 shaped; hyomandibular heavy and with a broad head that fits into a 

 groove in the pterotic and sphenotic; post-temporal present, absent, 

 or vestigial; pectoral arch with two ossified radials (actinosts; Starks, 

 1930^ p. 178), which are either separate or fused; entopterygoid 

 (Kindred, 1919, p. 92, pi. 6, fig. 16) or pterygoid (Regan, 1911, p. 

 562) greatly reduced or absent; ectopterygoid (mesopterygoid of 

 Regan, 1911, p. 562; Starks, 1926, p. 186) variously reduced, below 

 and partially medial to the palatine (in Noturus much reduced in 

 relative size) ; anterior vertebral complex containing five fused ver- 

 tebral elements; jaws nonpro tractile; eye lacking ossicles; gill rakers 

 present anteriorly on all five arches and posteriorly on the third and 

 fourth arches; rear faces of first and second arches smooth, and the 

 fifth bound posteriorly by a membrane; the four pairs of barbels, 

 include two which are mental, one is maxillary, and one is associated 

 with the posterior nares. 



The pelvic fin in ictalurids has eight, nine, or sometimes ten rays. 

 The pelvic rays are attached to the pelvic girdle; there are no free 

 radials. The pectoral fin possesses a hard spine, as does the dorsal 

 fin, but the number of soft, segmented rays (5 to 12) varies with 

 the species or species group. 



The anatomy of Amiurus [=Ictalurus\ has been described by 

 Macallum (1884), McKenzie (1884), McMurrich (1884), and R. R. 

 Wright (1884a-c). Kindred (1919) described the developing skull 

 and Starks (1926, pp. 185-186) reviewed its ethmoid region. Ex- 

 amination of cleared and stained specimens of representative icta- 

 lurids indicates that the ossified structures are much alike in the species 

 of the family and are essentially as described by Kindred and Mc- 

 Murrich. The differences observed in this study are regarded as 

 primarily of generic or specific significance. Regan (1911) listed some 

 of the major ones, indicating that Noturus differs from other icta- 

 lurids in the absence of the post-temporal and in the shortened lower 

 limb of the cleithrum. These structures are reduced in Noturus and 

 Prietella, and it is probable that they may also be reduced in the other 

 blind species. 



