632 

foramen majus and a foramen minus. The terms foramen praeoticum 
sive sphenoticum and foramen sphenoticum commune are thus ev- 
idently intended to be equivalent, but there is here again a confusion 
of a primary perforation of the cranial wall which leads from the 
cranial cavity into the trigemino-facialis chamber with a secondary 
foramen which leads from that chamber to the exterior. 
These two bands of cartilage having developed, the lateral wall 
of the trigemino-facialis chamber has three points of attachment to 
the cranial wall, and there are consequently three separate openings 
leading from the chamber to the exterior. One of these openings, the 
foramen sphenoticum minus of Gret’s terminology, gives passage to 
the nervus ophthalmicus profundus and the vena pterygoidea (jugularis), 
the nervus abducens issuing into the orbit along the ventro-mesial 
edge of the foramen, separated from it by a narrow band of cartilage. 
This foramen is accordingly the homologue, in the nerves and vessels 
it transmits, of the orbital opening of the myodome of my descriptions 
of Amia; for it must be borne in mind that this opening in Amia 
does not primarily transmit the nervi oculomotorius and trochlearis, 
those nerves issuing from it secondarily, because of the reduction in 
length of that part of the chondrocranium that lies between it and 
the foramen opticum. 
The second one of the three openings of the chamber of Cera- 
todus, the foramen sphenoticum majus, gives passage to all the 
branches of the nervi maxillo-mandibularis and lateralis trigemini, and 
to the vena and arteria temporalis, the latter artery being the carotis 
externa of current descriptions of other fishes. This foramen of Cera- 
toaus accordingly corresponds to the trigeminus, ophthalmicus super- 
ficialis and oticus foramina of my descriptions of Amia fused to form 
a single foramen. 
The third opening of the chamber of Ceratodus, the foramen 
prooticum basicraniale, gives passage to the ramus hyomandibularis 
facialis (which contains the lateralis facialis fibers), the ramus pala- 
tinus facialis, the arteria temporalis and the vena capitis lateralis, the 
latter vein receiving, while in the chamber or immediately after issuing 
form it, the vein formed by the union of the venae temporalis and 
cerebri media. This foramen of Ceratodus is accordingly the homo- 
logue of the posterior, or facialis opening of the trigemino-facialis 
chamber ‘of Amia fused wih the foramina for the external carotid 
artery and the ramus palatinus facialis. 
