464 ANATOMICAL TECHNOLOGY. 



The appearance of a division of the ectal layers of the pontile fibers into three groups, 

 cephalic, caudal and intermediate, the latter partly overlapped by the other two. 



The appearance of a faint band crossing the trapezium a little obliquely between the 

 origins of the NN. abducens (N. abd.) and facialis (N.f.). The distinctness of this band 

 varies. 



The origin of the N. hypoglossus (N. kg.) at the lateral border of the Area elliptica 

 (Ar. el.), which is thought by some (Am. Jour, of Neurology, etc., I, 102) to be the surface 

 of the oliva or " olivary body " of man. The determination of this point involves some 

 comparisons and sections which we have not yet made. 



The close association of the roots of the NN. glossopharyngeus (N. gph.), vagus (N. .) 

 and accessories (N. ac.) See Stowell (J.) and Chap. XI. 



The marked prominence of the ventro-lateral region of the metencephalic continuation 

 of the Columna lateralis myelonis (Clm. I.), forming an elevation to which I have applied 

 the provisional name Area omlis (Ar. ov,), but which is thought by some (Am. Jour, of 

 Neurology, etc., I, 102) to represent the Tuberculum Rolandii. 



The absence of any superficial decussation of the pyramides (py.). Hence, the F. ventri- 

 mesalis (F. vms.), or " anterior fissure," is uninterrupted. The F. ventrilateralis (F. vl.) is 

 deflected at the caudal end of the Area elliptica. 



1162. Fig. 4. The mesal surface of the right hemiencephalon ; x 2. Compare 

 Fig. 114. 



The general features are from the same brain as Fig. 3, but some are derived from 

 Prep's 290, 304 and 454. 



The surfaces shown in this figure are of four kinds, as follows ( 1137) : 



(1) The natural surfaces which are covered by pia. These are the mesal aspects of the 

 hemisphere (hem.} and the Lobus olfactorius (L. ol.\ 



(2) The natural mesal surface (Ar. spt.) of the right half of the septum lucidum, which, 

 in the cat, is in contact with its platetrope, or separated therefrom only by a thin layer of 

 connective tissue. We have never observed an interval corresponding to the pseuds- 

 caelia or " fifth ventricle " of man. 



(3) The natural endymal surfaces of the true ccelia or " ventricles." Of course the pro- 

 cceliae (" lateral ventricles ") do not appear. 



(4) The cut surfaces of the commissures and other parts which cross the meson or lie 

 upon it. In the cerebellum (cbl.), the relative areas of the ental alba and the ectal cinerea, 

 forming the arbor vitce (arb.), are indicated by the shading ; with less definiteness, the alba 

 is shown in the callosum (d.), the fornix (/.), the prcecommissura (prcs.), the postcommis- 

 sura (pcs.), the commis&ura habenarum (cs. h.), and the chiasma (ch.~). The section of the 

 medicommissura (mcs.) should appear as if composed, at least chiefly, of cinerea, but no 

 attempt has been made to indicate the nature of the cut surfaces of the Crista fornicis 

 (Crs.f.), the terma (t.), the hypophysis (hph.), the infundibulum (inf.), the conarium (en.}, 

 the optici and postoptici (op. and pop.), the valcula (vv.), the Crura cerebri (Cr. cZ>.), the 

 metatela (mttl.), or the rest of the epencephalon and metencephalon (mten.). The ex- 

 tent of the transverse fibers of the pons (pn.) should have been represented, at least 

 approximately. 



So much of the cephalic boundary of the aula (a.) as intervenes between the prcecom- 

 missura (pros.) and the crista (Crs.f.) is very thin, and is too indistinctly shown in the 

 figure. Neither here nor at any other point is there any such interruption of the wall as 

 would form a communication between the true creliae and the pseudocrelia or the ectal 

 surface of the brain. It is probable that the presence of such a communication as is 



