— 124 -^ 



of tlie orbital surface of the brain case. The postero-ventral portion of the orbit is thus here bounded 

 laterally by bone, this part of the orbit leading into and being continuous with the myodome. 



The PROÖTIC forms the middle three-fifths of the anterior edge of the brain case, the dorsal 

 fifth being formed by the sphenotic, and the ventral fifth by the short ascending process of the para- 

 sphenoid. At the middle of the entire edge there is a large foramen which perforates a thin plate-like 

 portion of the edge and leads directly into a small recess which lies on the orbital surface of the proötic 

 immediately dorso-lateral to the orbital opening of the myodome. This recess is the imperfectly 

 enclosed trigemino-facialis Chamber, and the large foramen that opens from it onto the lateral surface 

 of the brain case is the facialis opening of that Chamber. The lateral wall of the Chamber is reduced 

 to the slender column of bone that forms the anterior boundary of the facialis opening. Anterior to 

 this column of bone there is, on the projecting plate-like edge of the proötic, a process of variable 

 length and shape, already referred to, which projects upward toward the slight ridge on the orbital 

 surface of the alisphenoid. This latter ridge, as already stated, represents the parasphenoid leg of 

 the alisphenoid, the process of the proötic being a proötic outgrowth which has invaded the alisphenoid 

 membrane, there replacing, in this fish, the parasphenoid outgrowth found in Cottus. Across the 

 dorsal surface of this process of the proötic, or between it and the column that bounds the anterior 

 edge of the facialis opening, this depending on the shape of the process, the truncus trigeminus has 

 its exit from the chamber. 



The mesial wall of the trigemino-facialis chamber is perforated by three or four foramina; 

 two of them being large and the other one or two considerably smaller. Where there are four foramina, 

 one of the large ones transmits the root of the trigeminus together with the buccalis lateralis, the other 

 large one transmitting the motor root of the facialis together with the lateralis facialis and all of the 

 communis fibers of the trigemino-facialis complex; the two small foramina transmitting, one, the 

 ophthalmicus lateralis and the other the ciliaris profundi with the encephalic vein. Where there are 

 but three foramina, the ophthalmicus lateralis issues with the trigeminus and buccalis lateralis through 

 a partly separate portion of a single large foramen, the profundus and facialis always issuing through 

 independent foramina. The palatinus facialis issues through the facialis foramen, then turns mesially 

 along the floor of the trigemino-facialis chamber, and so enters the myodome. It is not here enclosed 

 in a separate canal. Directly mesial to the profundus foramen, the prepituitary portion of the mesial 

 process of the proötic is perforated by the oculomotorius, that nerve in 5 cm and 6 cm specimens of 

 Lepidotrigla, separating into its superior and inferior divisions before reaching its foramen. The 

 postpituitary portion of the mesial process is, in large specimens, either perforated or notched by a 

 foramen that transmits the abducens, that nerve passing directly from the cranial cavity into the 

 myodome. 



In the ventral edge of the proötic, is the internal carotid incisure. Posterior to that incisure 

 the ventral edge of the bone is capped its füll length with cartilage and abuts against the parasphenoid 

 in the deep groove along the lateral surface of the median longitudinal ridge on the dorsal surface 

 of the bone. 



On the internal surface of the proötic there is, as in Scorpaena, a trigemino-facialis recess, and 

 this recess lodges, as in Scorpaena, the communis, lateralis and profundus ganglia. 



On the lateral surface of the dorsal portion of the proötic there is a fossa, and immediately 

 anterior to the fossa a brace-like process, the process and fossa giving Insertion to the two internal 



