92 



brachyurus, issykkulensis, and phoxinus (TS 88 [1]); the posterior end of the bone extends 

 to the posterior portion of the dorsal part of the basioccipital in other Phoxinus (TS 88[0]). 

 In the outgroups, the parasphenoid bears a poorly-developed dorsal ridge on its dorsal 

 side, and a well-developed notch on the posterior margin of the ascending wing; the po- 

 sterior end of the bone is shallowly forked and extends to the posterior portion of the ven- 

 tral aspect of the basioccipital's dorsal part. 



Basioccipital (Figs.49A-B, 50, 54A-B, 55A-D). In cyprinids, the basioccipital is placed 

 at the most posteroventral portion of the neurocranium, and forms the posterior base of 

 the braincase. It sutures with exoccipital dorsally and laterally, prootic anteriorly, and pa- 

 rasphenoid anteroventrally. 



The basioccipital is morphologically a complex bone in cyprinids. (It might be the most 

 complicated in all the bones in cyprinids.) Basically, two parts can be recognized from 

 the bone - i.e., dorsal portion, and a pharyngeal process. The dorsal portion appears as a 

 flat plate and is the anterodorsal portion of the basioccipital. The pharyngeal process is 

 the portion located at the posteroventral side of the dorsal portion of the basioccipital 

 (Figs.54A-B, 55A-D). The pharyngeal process consists of a bony plate (pharyngeal pad) 

 for the attachment of a horny pad, a process located at the posterior margin of the pharyn- 

 geal pad (posterior process) (Ramaswami 1955a), and an anterior process (in some spe- 

 cies). The posterior side of the pharyngeal pad forms the concave condyle articulating 

 with the anterior side of vertebra 1 . The dorsal aorta passes the fenestra formed between 



Fig. 54: Basioccipital bone of 

 Phoxinus neogaeus (KU 

 8521. 53.0 mm SL) (A: ven- 

 tral view; B: dorsal view). 



A B Scale bar = 1 mm. 



