89 



In Phoxinus, the dorsal portion of the supraoccipital is a flat plate, the posterior portion 

 of the flat plate is bent ventroposteriorly. Viewed dorsally, the middle of the anterior mar- 

 gin of the supraoccipital is deeply concave. Therefore, two anterior processes are present 

 at the lateral portion of the anterior margin of the bone. The crest at the posterior part of 

 the flat plate extends posteriorly. The crest is poorly developed, and is attached by liga- 

 ments from the Weberian apparatus and the supraneural bones. Posteriorly, the bone is tri- 

 angular in shape. The posterior surface of the supraoccipital is attatched by epaxial 

 muscles. Four concavities are present on the ventral aspect of the bone (Fig.51A-C). 

 Variation of the supraoccipital within Phoxinus includes the anterior margin and the con- 

 cavities at the ventral aspect of the bone. In P. brachyurus, issykkulensis, phoxinus, erythro- 

 gaster, tennesseensis, oreas, and neogaeus, a process is present at the middle of the anterior 

 margin (between the two anterior processes at the anterior margin) (TS 80[1]). The pro- 

 cess is well developed in all of the above species, except P. erythrogaster in which the 

 process is very short. In P. cumberlandensis and eos, no process is present at the middle 

 of the anterior margin between the two anterior processes (TS 80[0]). In P. cumberlan- 

 densis, the four concavities on the ventral side of the supraoccipital are more developed 

 and deeper (TS 8 1 [ 1]) than that in other species of Phoxinus (TS 8 1 [0]). 

 A small bar-like medial extrascapular (Fig.44B) is present on the supraoccipital in P. 

 brachyurus (TS 82[1]). This medial extrascapula is not present in other species of Pho- 

 xinus (TS 82[0]; Fig.45A). 



In the outgroups, the middle of the anterior margin of the supraoccipital bears no process, 

 the concavities on the ventral side of the supraoccipital are small and shallow; the medi- 

 al extrascapula is absent on the supraoccipital. 



A 



c 



Fig. 52: Vomer of Phoxinus (a: 

 ventral view; b: dorsal view). 

 A: P. phoxinus (CNUC un- 

 cat., 76.0 mm TL); B: P. 

 etythrogaster (KU 5773; 51.5 

 mm SL); C: P. oreas (KU 

 3259, 55 mm SL, ventral 

 view); D: P. eos (KU 12255, 

 43.0 mm SL, ventral view). 

 Scale bars = 1 mm. 



B 



D 



