TvR^MU, ^forp/lo/oi;■y of ///(' Avian Brain. 51 



hedron, with two plane and five convex surfaces. Two faces 

 are formed by the, practically plane, sub-parallel, sides. A 

 third face extends cephalo-dorsad from the caudad extremity 

 of the epencephalon to the dorsal extremity of the same. 

 A fourth face extends cephalo-ventrad from this place to the 

 pineal body. From this place, a fifth face extends, almost 

 perpendicularly, cephalo-ventrad to about where the meten- 

 cephalon joins the diencephalon. Thence a sixth face extends 

 ventro-caudad to the ventral extremity of the epencephalon. 

 The solid is closed by the seventh face, which extends caudo- 

 dorsad from this place to the caudal extremity of the epen- 

 cephalon. The last five faces are ectally convex and cre- 

 nated. In most cases, faces three to seven are of about the 

 same size (Plate VII, Fig. 3). 



Convolutions. — The epencephalon is indented by several 

 transverse fissures, which extend entad from the periphery 

 almost to the ventricle. Near the surface, these fissures are 

 usually increased by the intercalation of one or more fissures 

 between each of the above. Corresponding to each of these 

 fissures, there is a transverse convolution. It is the presence 

 of these convolutions which gives the above-mentioned faces 

 a crenated appearance (Plate VII, Fig. 3). 



Flocculi. — These are two flaps, one of which projects 

 from each of the lateral surfaces of the epencephalon. They 

 arc situated at a short distance caudad to the optic lobes and 

 immediately cephalad to the metencephalon. In the Anatidce 

 and ArdeidcE (Plate V, Figs. 4, 5, 6, 9), these flaps are sub- 

 triangular; in the Passcrcs, Picaricc, Strigidcc, etc. (Plate 

 V, Figs. I, 7, 8, 10), these flaps are sub-rectangular. P^ach 

 flocculus is almost completely imbedded in a special cavity 

 of the skull. 



/ cniriclc. — In the center of the epencephalon there is a- 

 small ventricle, which is connected to the fourth ventricle 

 by a narrow neck. 



Proportions. — In the Anatidcc (Plate V, Fig. 5), the 

 epencephalon is wider than long; in all the other families 



