328 



secondary one. This will be again referred to; but I wish to here 

 further call attention to the singular apparent relations of the nerves 

 to the process, as shown and described by Gaupp. The ophthalmicus 

 (orbito-nasalis) trigemini and the hyomandibularis facialis apparently 

 pass, as a single trunk, across the same edge of the process ; yet they 

 actually lie, the one morphologically anterior, and the other morpho- 

 logically posterior to the process. The abducens is said by Gaupp 

 to run forward under the process, enclosed in the sheath of the oph- 

 thalmicus (orbito-nasalis); yet the abducens must lie morphologically 

 posterior to the process, while the ophthalmicus, though having its 

 apparent origin from the same ganglion, and running forward enclosed 

 in the same sheath, lies morphologically anterior to it. This will all 

 be at once apparent if one imagines the ascending process shifted up- 

 ward, and the foramen of the trigeminus shifted forward beneath it. 

 And it will be still further simplified if one assumes, with Gaupp 

 (p. 386), that a prefacial, basi-capsular connection of the otic capsule 

 with the basal plate, which exists in certain Urodeles, has disappeared 

 in Rana. 



That the ascending process of the quadrate does have primarily 

 a dorsal and not a ventral connection with the skull, is shown, aside 

 from the relations of the nerves to the process, by its development in 

 Necturus. In this Urodele, according to Platt (23), two cranial car- 

 tilaginous bars develope on each side of the head, one ventral and 

 one dorsal. The ventral bar is the trabecula ; the dorsal bar is called 

 by her the "dorsal bar of the crista trabeculae". The opticus, oculo- 

 motorius, trigeminus and abducens all pass outward from the cranial 

 cavity between these two bars, lying dorsal to the one, and ventral 

 to the other. The ascending process of the quadrate grows upward 

 and fuses with the dorsal bar before either the quadrate or the dorsal 

 bar become connected at any place with the ventral bar. Later the 

 two bars become connected with each other, at and near their anterior 

 ends, by three vertical cross bars. Still later, the dorsal bar, by a 

 posterior prolongation, acquires a connection with the anterior wall of 

 the otic capsule; the otic process of the adult thus seeming to be 

 a part of the skull and not a part of the quadrate. Three openings 

 are thus formed, which transmit, one the opticus, one the oculomotorius, 

 and the other the united trigeminus and abducens. 



The trigeminus ganglion of Necturus lies immediately in front of 

 the otic capsule, dorsal to the ventral trabecular bar ; and the ascending 

 process of the quadrate arches over it, seemingly enclosing it, much 

 as the side wall of the trigemino-facialis chamber encloses the trigeminus 



