194 EDWARD L. RICE 
septalis nur in loser Verbindung mit dem Septum standen. Indem 
auf der Grundlage eines solchen Zustandes die Nasenhdhle bei den 
Sdugern eine gréssere Entfaltung erfuhr, konnte die Hinterwand nach 
hinten hin vorgeschoben werden, wodurch ein Theil des frittheren 
Septum interorbitale (der reptilischen Si&iuger-Ascendenten) in intra- 
nasale Lage kam. (’08 a, p. 776.) 
5. Floor of ethmoid region 
The cartilaginous floor of the nose (fig. 2), as already noted, is 
extremely incomplete, and the nasal capsule would be largely 
open ventrally except for the very perfect adaptation of the 
vomer (fig. 2, os vo.) to supply the deficiency of cartilage. 
Through almost its entire length the ventral edge of the nasal 
septum is free from all other cartilages; only at the extreme 
anterior end is it fused with an insignificant horizontal plate of 
cartilage, the solum nasi, in the narrow sense, or lamina trans- 
versalis anterior. ‘Toward the posterior this floor separates 
almost immediately from the septum and forms, on each side, 
a little saucer of cartilage, the capsule of Jacobson’s organ (fig. 2, 
caps.jac.), Which supports the anterior half of Jacobson’s organ. 
The hinder margin of this saucer is divided into three rather 
definite lobes. The innermost lobe has a thin edge and termi- 
nates further forward than the others;lateral to this the cartilage 
is swollen into a rounded knob, which pushes up into Jacobson’s 
organ, forming its concha (figs. 2 and 28, co.jac., more conspicuous 
a few sections further back than fig. 28); the outermost lobe 
(fig. 2, c.ect.) is also considerably thickened and extends furthest 
to the posterior, although to no such distance as the corresponding 
element, cartilago ectochoanalis, in Lacerta. 
In stage 5 this capsule of Jacobson’s organ has no further 
connections, but in a later stage (fig. 27) its lateral margin is 
continuous with the lateral wall of the nasal capsule, to form 
the incomplete zona annularis already mentioned. In Lacerta 
its median lobe extends back continuously into the paraseptal 
cartilage, a thin strip of cartilage which lies close alongside the 
lower edge of the septum, but without contact, and is continuous 
posteriorly with the planum antorbitale. Alike in Eumeces and 
