128 



the centrum of the third vertebra. The posterior ramus is elongated and extends posteri- 

 orly and is concave. The posterior ramus is more slender and elongate in P. neogaeus and 

 erythrogaster (TS 1 82 [ 1 ] ) than in other species of Phoxinus and in the outgroups (TS 

 182[0]). 



Intermuscular bones. Intermuscular bones (myoseptal or intermyoseptal bones) 

 (Fig.81) are placed in the myoseptum between two myotomes. In epaxial myotomes, the 

 intermuscular bones are present from the first (or second) vertebral segment to the cau- 

 dal fin base. In hypaxial myotomes, the bones exist from the posterior of the body cavi- 

 ty to the caudal fin base. Generally, intermuscular bones are thin and slender in shape, 

 with or without a fork at the anterior end of the bones in epaxial myotomes or dorsal end 

 of the bones in hypaxial myotomes. Some intermuscular bones are expanded at their po- 

 sterior ends forming brush-like structures. No variations with phylogenetic significance 

 are present among the species of Phoxinus. 



Other supraneural bones (Figs.76A-D. 77A-C). Other supraneural bones are located 

 median at the dorsal side of the body, from posterior of the supraneural bone 3 to the an- 

 terior of the origin of the dorsal fin in all Phoxinus species. The supraneural bones are 

 plate-like, and roughly rectangular in shape. 



Supraneural 4 is located between neural spine 5 and the supraneural 3. It is large and ex- 

 tends to the grooved portion of the supraneural 3 in P. cumberlandensis (TS 1 83 [ 1 ] ). It is 

 small and extends to the dorsal of neural spine 4. but not to the grooved portion of su- 

 praneural 3 in all other species of the Phoxinus and in the outgroups (TS 183[0]). This 

 supraneural bone is poorly developed, very small, and its anterior edge is far away from 

 the posterior margin of neural spine 4 in P. phoxinus. In P. enthrogaster, supraneural 4 

 is pieced into two part, the anterior part is located on the dorsal to neural spine 4. and far 

 away from neural spine 5; the posterior part is placed between neural spines 4 and 5 (TS 

 184[1]). This condition is absent in other species of Phoxinus or in the outgroups (TS 

 184[0]). 



A single supraneural is present between two neighbor neural spines from neural spine 5 

 to the neural spine just anterior to the first dorsal pterygiophore. The supraneurals de- 

 crease in size posteriorly. The most posterior few supraneurals are very small. The last 

 one just anterior to the first pterygiophore of the dorsal fin is absent in some specimens 

 of Phoxinus. 



Vertebrae 



The vertebrae of species of Phoxinus can be divided into precaudal and caudal elements 

 as defined below. Between the "normal" precaudal and caudal vertebrae two or three ver- 

 tebrae are present as transitional elements (see below). The total number of the vertebrae, 

 including numbers of the precaudal (the transitional elements included), and caudal ele- 

 ments, is given for each species in the species accounts. Number of vertebrae varies from 

 37 to 40. of which 18 to 20 are precaudal ones, and 17 to 21 are caudal ones. 

 Generally, the precaudal vertebrae, except the anterior four elements which were discus- 

 sed in the "Weberian Apparatus", are almost monomorphic. Dorsally. each vertebra bears 

 a neural arch and spine directed posterodorsally, a pair prezygopophyses. and a pair postzy- 



