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to be the homologue of the transverse prepituitary bolster of Amia. The lateral edge of the plate, 

 in Lacerta, is connected, on either side, by the pila metoptica, with the taenia parietalis media, this 

 latter structnre being a horizontal bar of cartilage that forms part of the side wall of the cranial cavity. 

 The pila metoptica forms part of the anterior boundary of the fenestra metoptica, which transmits 

 the oculomotorius and trochlearis nerves; those nerves thus undoubtedly running forward lateral 

 to the pila metoptica, into the orbit. The cartilaginous pila metoptica of Lacerta thus corresponds, 

 in its relations to these two nerves, to the basisphenoid leg of the alisphenoid bone of Lepidosteus, 

 and to the fibrous tissue that, in Amia, represent the same leg and forms the mesial boundary of the 

 tall orbital opening of the myodome. In Amia, the relations of the two nerves to the basisphenoid 

 leg of the alisphenoid are not positively indicated, that leg being represented by an undefined 

 portion of a continuous membrane. In teleosts, the oculomotorius issues, in all the fishes I have 

 examined, posterior to the sutural connection of the alisphenoid with the basisphenoid, and 

 hence lies posterior to the basisphenoid leg of the alisphenoid. The trochlearis has however 

 in teleosts the same indefinite relations to the basisphenoid leg of the alisphenoid that it has 

 in Amia, for it issues along the ventral or ventro -anterior edge of the alisphenoid, but anterior 

 to the sutural connection of that bone with the basisphenoid. It must accordingly either lie 

 anterior to the basisphenoid leg of the bone, or perforate an unossified portion of that leg; probably 

 the latter. 



In Lacerta the hypophysis lies posterior to the subiculum infundibuli, between it and the 

 crista sellaris. Lateral to the crista sellaris, the nervus abducens pierces the basal parachordal plate, 

 near its anterior edge, and, running forward in the plate, opens on its very edge; the foramen not 

 being shown in ventral views. From there the nerve must run forward dorsal to the trabeculae, 

 as it does in the Frog (Gaupp, '93a) and Necturus (Platt, '97), and in this part of its course it must 

 lie between the trabeculae and an overlying membrane of some kind, doubtless a somewhat differ- 

 entiated layer of the dura mater. This membrane would certainly underlie the hypophysis and so 

 represent a membranous floor of this part of the cranial cavity, but to what extent it is developed 

 or differentiated, I can not determine from the literature at my disposal. Assume it to be well devel- 

 oped. It would extend between the subiculum infundibuli and the crista sellaris, forming a mem- 

 branous fossa around the hypophysis, and leaving a space between itself and the underlying cartilage 

 of the skull. This space must be traversed by the vein that is said by Gaupp ('93b, p. 571) to run 

 forward from the hypophysis into the orbit, and which is the evident homologue of the pituitary 

 vein of my descriptions of Amia, Lepidosteus and Scorpaena. The space must, furthermore, be 

 traversed by the carotid artery, which artery having either traversed the hypophysial fenestra or 

 a closely adjoining and independent foramen, is said by Gaupp (1. c. p. 571) to run forward close 

 to the brain; thus doubtless passing dorsal to the subiculum infundibuli. These conditions in Lacerta 

 are thus all too similar to those in the fishes referred to not to Warrant the following conclusions: 

 (1) that the cartilaginous floor of the cranial cavity of Lacerta is probably the homologue of the 

 ventral floor of the myodome of fishes; (2) that there is, in the pituitary region of this skull, and 

 dorsal to the cartilaginous floor, a space of uncertain dimensions which corresponds to a part, if not 

 to the whole, of the myodome of fishes; (3) that the hypophysial fenestra of Lacerta is consequently 

 the strict homologue of the hypophysial fenestra of Lepidosteus; and (4) that the subiculum infundi- 

 buli is the homologue of the basisphenoid cartilage of Scorpaena, and hence of the transverse pre- 

 pituitary bolster of Amia. 



