262 



Leaving the second one of these two membranes out of con- 

 sideration for the moment, it is seen that the ganglionic complex of 

 the so-called trigeminal nerves is practically enclosed in a part of 

 the membranous cranium, in a chamber resembling the upper lateral 

 chamber of the eye-muscle canal of Amia. The nervus facialis tra- 

 verses a posterior and somewhat separate portion of this same 

 chamber. The entire chamber may therefore be called the trigemino- 

 facialis chamber. From this chamber, in Bdellostoma, the ramus 

 ophthalmicus issues by an anterior foramen , the ramus palatinus 

 trigemini by an an tero- ventral foramen, the truncus maxillo- 

 mandibularis by a ventral foramen, the nervus facialis by a postero- 

 ventral foramen, and what I consider as the ramus buccalis lateralis 

 by a lateral foramen. The several apparent roots of these trigemino- 

 facialis nerves all pierce the thick mesial membranous wall of the 

 chamber, that wall forming the side wall of the brain case and thus 

 corresponding to the membranous mesial wall of the upper lateral 

 chamber of the eye-muscle canal of Amia. 



In Lepidosiren a similar chamber is called by Bridge (6) u the 

 Gasserian recess", and is said by him to be a lateral diverticulum of 

 the cranial cavity situated at the junction of the trabecular and 

 periotic cartilages. 



The so - called trigeminal ganglionic complex of Bdellostoma 

 is separated into two distinct portions, an anterior dorso-mesial 

 portion, and a posterior ventro-lateral portion. In addition to these 

 two ganglionic portions there is another, postero-ventral portion of 

 the complex, that is not ganglionic. The complex is connected with 

 the medulla by four apparent roots, two of which are formed by the 

 fusion of several rootlets, each of these rootlets piercing the mem- 

 branous cranium by a more or less distinctly separate foramen. These 

 four roots are : 1) the root of the ramus ophthalmicus, 2) the root of 

 the palatinus and maxillo-mandibularis trigemini, and which may be 

 called the maxillo-mandibularis root of the complex; 3) the motor 

 root of the trigeminus; and, 4) what I take to be the root of the 

 nerve that I have above referred to as probably being the buccalis 

 lateralis, though the fibres of that nerve could not with any certainty 

 be traced directly to the root. 



The ophthalmicus root arises from the anterior surface of the 

 projecting, process-like anterior end of the medulla, as Müller (19) 

 shows it. It arises as a single apparent root, runs forward and 

 laterally, pierces the membranous side wall of the cranium by a single 

 foramen, and, entering the trigemino-facialis chamber, immediately 



