-JSYNONYMS AND REFERENCES. 477 



The contracted portion of the brain between the prosencephalon and the Lobus olfac- 

 torius. Its ventral surface is continuous caudad with the Tractus rhinalis. 



§ 1217. Delta (fornicis), (as.), m.—¥\g. 120 ; PI. IV, Fig. 14. 



The triangular entocwlian area of the ventro-caudal surface of the furniz, constituting 

 the roof of the aula. Its base coincides with a line between the portae, and its two other 

 s'.des are ripm, lines of reflection of the endyma upon the intruded auliplexus. It does not 

 appear to have been observed prior to the senior author's paper (.9). 



§ 1218. Diacoelia (az.), dc— Fig. 110-113, 117, 120, 133 ; PI. II, Fig. 4; PI. Ill, Fig. 7; 

 PI. IV, Fig. 16 ; § 1143. Gray, A, 629 ; Quain, A, II, 546. 



/%».— Ventriculus tertius, third ventricle, middle ventricle, mediventricle. 



The irregular mesal cavity between the thalami, bounded dorsad by the diatela, post- 

 commissura and conarium ; ventrad by the diencephalic portion of the Crura cerebri, the 

 albicantia, Tuber cinereum and ternia (reinforced by the chiasma), continuous cephalad 

 with the aula and caudad with the mesocoelia. Most of its dorsal portion is occupied by 

 the niedicommissura. The diacoelia represents the cavity of the primitive " anterior cere- 

 liral vesicle." 



The reasons for adopting this and the other names for the encephalic cavities are stated 

 ill § 1064 and the papers there referred to. 



§ 1219. Diaplexus, dpx.—Tig. 112, 113, 117, 133; PI. II, Fig. 4; PI. IV, Fig. 16; 

 § 1143. Gray, A, 628 ; Quain, A, II, 545. 



8yii. — Plexus choroideus ventriculi tertii, plexus choroideus medius. 



The string-like vascular plexus extending the entire length of the diacoelia on each 

 side ; it is sligiitly attached to the diatela and has firmer connections by vessels at its 

 ends, which are not clear to us. It is continuous cephalad with the avliplexus. For the 

 name, see § 1066. 



§ 1220. Diatela («z.), dtl.—F\g. 111-113, 117, 122; PI. Ill, Fig. 10. Reichert, A, 155. 



The membranous or atrophied nervous roof of the diacoelia. Its exact composition has 

 not been ascertained, but it seems to consist of something more substantial than endyma. 

 Judging from current statements respecting the roof of the " third ventricle," this delicate 

 tela is usually torn oflF with the fornix, and no notice is taken of the ragged lines of its 

 separation along the Sulcus liahenm on each side. In the Museum of Cornell University, 

 however, there are preparations of the cat and rabbit which show the diatela after the 

 removal of the fornix and velum, while the ripas or lines of reflection are apparent upon 

 many others, as in that shown in PI. Ill, Fig. 7. 



§ 1331. Diencephalon (az.), den.— 'Fig. 88, 110-113, 116-118, 132; PI. II, Fig. 3, 4; 

 PI. Ill, Fig. 6, 7, 9-11 ; PI. IV, Fig. 16, 18, 19 ; § 1061. Gray, A, 111 ; Quain, A, II, 755. 



Syii. — Deutencephalon, thalamencephalon, interbrain, 'tweenbrain. 



The encephalic segment between the mesencephalon and the prosencephalon. Its 

 cavity is the diacoelia (" third ventricle "), and its chief constituents are the thalami. 



§ 1333. Dura (mater), tf.— Fig. 88 ; § 1104. Gray, A, 606 ; Quain, A, II, 569. 



The firm membrane which lines the cranial cavity, is reflected upon the osseous tento- 

 rium (§ 553), and is produced between the hemispheres as the falx cerebri ; it is an ento- 

 cranial periosteum. 



Notwithstanding its feminine form, dura is frequently employed without the substan- 

 tive mater. 



§ 1333. Eminentia auditoria, Em. aa.— PI. I, Fig. 3; PI. II. Fig. 3 ; § 1140. 



The name was suggested by the senior author {14r, 536) for the distinct elevation just 

 laterad of the trapezium, whence springs the N. auditorius. It is continuous mesad with 

 a Tractus auditorius, which does not appear in the figures. 



