104 



from the mesial line of the dorsal side of the ventral plate. The variations of the urohyal 

 among Phoxinus species include the anterior fork, and the ventral and dorsal plates. 

 The anterior fork is deep in Phoxinus neogaeus, phoxinus, and brachyurus (TS 109[1]). 

 its depth is more than two times of the neck length (from the most posterior point of the 

 anterior fork to the anterior end of the ventral plate). The anterior fork is shallow and 

 equals to (or less than) the neck length in other species of the Phoxinus (TS 109[0]). 

 The ventral plate is the main part of the urohyal. Generally, its posterior portion is broa- 

 der than its anterior one. In P. brachyurus, neogaeus, and phoxinus, its posterior margin 

 is convex (TS 110[1]). In other species of the Phoxinus, however, the posterior margin is 

 concave (TS 110[0]). In P. eos, the concave posterior margin bears a process at middle. 

 The dorsal plate is perpendicular to the dorsal side of the ventral plate. It gradually in- 

 creases in height posteriorly. Therefore, its posterior portion is higher than its anterior por- 

 tion and the dorsal plate tends to be triangular in shape. In P. cwnberlandensis, oreas, 

 erythrogaster, and tennesseensis, the dorsal plate is high and short, its posterior margin is 

 at the level of the most anterior point of the concave posterior margin of the ventral plate 

 (TS 111[1]); in P. brachyurus, issykkulensis, phoxinus, and neogaeus, the dorsal plate is 

 lower, its posterior margin is at the level of the most posterior point of the convexed po- 

 sterior margin (TS 1 1 1 [0]); in P. eos, the dorsal plate is lower and long, its posterior mar- 

 gin extends posterior to the posterior margin of the ventral plate. 



In the outgroups, the depth of the anterior fork is less than the elongated neck length, the 

 posterior margin of the ventral plate is shallowly concave; the dorsal plate is low and long, 

 its posterior margin extends beyond the posterior margin of the ventral spread. 



Branchiostegals (Fig.64A-E). In cyprinids, the branchiostegals include three pairs of 

 thin, elongated plate-like slender dermal bones, branchiostegals 1, 2. and 3 (from the an- 

 terior to the posterior), and are placed at the ventrolateral side of the head. 



Branchiostegal 1 (Fig.64A-E) is an elongated bone articulating with the anterior cerato- 

 hyal. The anterior end of branchiostegal 1 is concave in P. neogaeus, issykkulensis, pho- 

 xinus, oreas, tennesseensis, and cwnberlandensis (TS 112[1]); the anterior end is convex 

 in P. erythrogaster, eos, brachyurus. and in the outgroups (TS 112[0]). The relative posi- 

 tion of the bone to the anterior ceratohyal does not vary significantly among the Phoxi- 

 nus species. 



Branchiostegal 2 (Fig.64A-E) articulates with posterior end of the anterior ceratohyal. The 

 relative position between these two bones does not vary significantly among Phoxinus 

 species. The anterior end of the branchiostegal is sharp in P. phoxinus, erythrogaster, 

 brachyurus, and eos (TS 113[0]) which is similar to that in the outgroups. The anterior 

 end of the branchiostegal 2 is blunt in other species of Phoxinus (TS 113[1]). 



Branchiostegal 3 (Fig.64A-E) is the most posterior element of the branchiostegal rays. The 

 position where the branchiostegal contacts the ceratohyals varies among species of 

 Phoxinus. In P. issykkulensis, phoxinus, erythrogaster, neogaeus, and brachyurus. the an- 

 terior end of the branchiostegal 3 articulates with both the anterior portion of the poster- 

 ior ceratohyal and the posterior portion of the anterior ceratohyal (TS M4[l]); 

 branchiostegal 3 articulates with the anterior end of posterior ceratohyal only in other spe- 



