83 



Ventrally, the sphenotic bears three to five concavities which are separated from one ano- 

 ther by bony ridges. In P. phoxinus and cumberlandensis, three concavities are present 

 (TS 69[2]). In P. eos and erythrogaster, there are four concavities (TS 69[0]). Five con- 

 cavities were found in other species of Phoxinus (TS 69[1] ). 



In the outgroups. the sphenotic is not deeply concave at the anterior portion of the late- 

 ral margin, and bears four concavities on its ventral side. 



Prootic (Fig.46A-D). In cyprinids. the prootic is placed at the ventral side of the neu- 

 rocranium. It sutures with sphenotic anterodorsally, pterotic and epioccipital posterodor- 

 sally, exoccipital and basioccipital posteriorly, parasphenoid ventrally, and pterosphenoid 

 anteriorly. 



In Phoxinus the prootic is an irregularly shaped plate-like bone forming a major portion 

 of the posterolateral wall of the braincase. The prootic bears a notch at its anterior mar- 

 gin. This notch and the one at the posterior margin of the pterosphenoid form the trige- 

 minal foramen. The notch on the anterior margin of the prootic is deeper in P. erythrogaster 

 and oreas (TS 70[1]) than in other species of Phoxinus (TS 70[0]). The prootic also bears 

 a facial foramen at its middle portion. A process is present on the dorsal margin of the 

 prootic in some Phoxinus species. The process is well-developed in P. neogaeus, less de- 

 veloped in P. oreas, erythrogaster, and cumberlandensis (TS 7 1 [0] ). and it is absent in 

 other species of the genus (TS 71 [1]). Ventrally, the prootic is forked and articulates with 

 the parasphenoid. 



In the outgroups, the prootic bears a shallow notch at its anterior margin and a process at 

 its dorsal margin. 



Epioccipital (Fig.47A-C). This bone was first named as epiotic by Huxley (1858). Pat- 

 terson (1975) showed that the bone is an ossification of the occipital arch invading into 

 the otic region, thus he proposed "epioccipital" to replace "epiotic" for the bone. In cy- 

 prinids, the epioccipital is a paired endochondral bone, located at the posterior portion of 

 the neurocranium. Dorsally, the epioccipital sutures the supraoccipital mesially. pterotic 

 laterally, and parietal anteriorly. Ventrally. the epioccipital sutures the exoccipital and proo- 

 tic mesially, the exoccipital and pterotic posteriorly, and pterotic laterally. Posteriorly, the 

 epioccipital sutures the exoccipital ventrally, supraoccipital mesially, and the pterotic la- 

 terally. 



In cyprinids, a subtemporal fossa is formed by the posterior side of the prootic as the in- 

 ner wall of the fossa, the dorsoposterior portion of the pterotic. and epioccipital as roof 

 of the fossa. In most cyprinids. including Phoxinus and the outgroups, the fossa is relati- 

 vely deep and circular or oval in shape (Howes 1981). 



In Phoxinus, the epioccipital is a complicated bone in morphology. Dorsally. the bone is 

 plate-like with a process at its posterior edge. The general shape of the bone in a dorsal 

 view varies among species. In P. cumberlandensis, the epioccipital is much narrower at 

 its anterior portion than at its posterior portion and. therefore, is triangular-shaped (TS 

 72[1]). In other species of the genus, the bone is more or less rectangular (TS 72[0]). In 

 P. phoxinus, brachyurus, and issykkulensis. the process on the posterior margin is large 

 and blunt (TS 73[1]; Fig.47B). In other species of Phoxinus. the process is narrow and 

 elongated (TS 73[0]), either sharp (e.g., P. cumberlandensis). or blunt (e.g.. P. neogaeus). 



