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ventral end of each of these ridges projects, as a sniall process, toward the dorsal end of the ascending 

 process of the parasphenoid, and is connected by fibrous tissue with the dorsal end of that process, 

 this tissue bridging, to reach the parasphenoid, a narrow intervening portion of the orbital surface 

 of the proötic. The tissue related to the antero-mesial ridge is always more strongly developed than 

 that related to the postero-lateral one, being almost ligamentous in character. In one specimen it 

 had even become entirely ossified by invading growths from the alisphenoid and parasphenoid, a 

 complete bony foramen thus being formed which is the homologue of the internal jugular foramen 

 of AUen's ('05, p. 81) descriptions of Ophiodon. When the ligamentous tissue does not ossify, and 

 that is the usual condition in the specimens that I have examined, the foramen becomes an internal 

 jugular notch. The bottom of this notch, or the mesial border of the foramen when there is a foramen, 

 is usually, but not always marked by a slight ridge on the proötic; and this ridge, where there is 

 simply a notch, forms the dorso-lateral corner of the orbital opening of the myodome, and separates 

 that opening from a groove on the posterior wall of the orbit. This groove lies on the orbital surface 

 of the proötic, leads dorso-postero-laterally into the trigeminus opening of the trigemino-facialis 

 Chamber, and lodges not only the internal jugular vein, but also the truncus ciliaris profundi. Be- 

 cause of the name given to the foramen (or notch) that forms its antero-mesial boundary, the groove 

 can be called the internal jugular groove. Coming along this groove, the truncus ciliaris profundi 

 passes through the internal jugular notch, mesial to the spanning ligament, and then turns forward, 

 in the orbit; the nerve thus entering the orbit mesial to, and hence morphologically anterior to, the 

 spanning ligament. The oculomotorius traverses a foramen in the proötic the external aperture 

 of which lies immediately antero-mesial to the internal jugular notch, and then runs forward in the 

 orbit, thus also lying mesial and hence morphologically anterior to the band of ligamentous tissue. 

 The trochlearis has similar relations to the band of tissue, while the trigeminus and lateralis nerves 

 issue, and always lie, lateral, and hence morphologically posterior to it. The band of ligamentous 

 tissue and the associated process-like ridge of the alisphenoid, thus together correspond exactly, 

 in their relations to these cranial nerves, to the pedicle of the alisphenoid of Amia; and if, in Scor- 

 paena, the process of the alisphenoid were alone to be prolonged, by ossification of the ligament, its 

 ventral end would rest upon the ascending process of the parasphenoid, and, interno-posterior to that 

 process, upon a portion of the lateral bounding wall of the orbital opening of the myodome, exactly 

 as it does in Amia. The process and band, together, are thus quite certainly the homologue of the 

 pedicle of the alisphenoid of Amia. 



That small part of the aUsphenoid of Scorpaena that lies ventral to its slightly developed 

 pedicle must then correspond to that flange of the alisphenoid of Amia (AUis, '97a, fig. II) that lies 

 internal to the well-developed pedicle of the bone of that fish. In Amia this flange of the alisphenoid 

 gives attachment to the dorsal edge of the tough membrane that, in that fish, forms the lateral wall 

 of the cranial cavity and the mesial (morphologically anterior) wall of the tall orbital opening of the 

 myodome. Ventrally this membrane is closely attached (AUis, '97a, p.494) to the dorsal surface of the 

 transverse cartilaginous prepituitary bolster of the fish; and in this part of the membrane, or perhaps 

 partly also in tissues that remain after the resorption of the cartilaginous bolster, the body and pediclo 

 of the T-shaped basisphenoid of teleosts are developed. In both Scomber and Scorpaena the ventral 

 edge of the alisphenoid suturates with the lateral edge of the body of the basisphenoid; this showing 

 that a portion of the membrane that forms the antero-mesial wall of the orbital opening of the 

 myodome of Amia is alisphenoid membrane, and potentially a part of the alisphenoid bone. 



