NAMES OF TEE ENCEPHALIC CAVITIES. 407 



The Greeks designated either a cardiac or an encephalic cavity by the name KoOua, and 

 the senior author has proposed (.9, 125, 14, 540) to substitute it for ventriculus, and to des- 

 ignate the several encephalic cavities by terms formed by its combination with tlie charac- 

 teristic prefixes of the encephalic segments. This gives us rJUnocalia, proccelui, diaccBlia, 

 mesficailia, epiccelia and metacoelia. These terms are capable of inflection, and the longest 

 of them is no longer than the Latin ventriculus, which requires a prefix or qualifying 

 word. Finally, when the student has once learned the order and significance of the names 

 of the encephalic segments, he has only to acquire a single term and apply thereto the char- 

 acteristic prefixes with which he is already fainiliar. 



§ 1065. Aula and Porta. — These names were proposed by the senior author (o, 0, 14:, 

 540) upon the following grounds :^ 



(1) To substitute brief single words for the phrases: "ventriculus communis," " veyi- 

 triculus lohi communis," cavity of the " cerebral rudiment," unpaired hemisphere vesicle 

 or "secondary forebraiu," mesal part of the "common ventricular cavity," foramen 

 Monroi, etc. 



(2) Because the phrase most commonly employ eA, foramen Monroi, is used to designate 

 at least tliree different caciiics or orifiies : (A) The cavity by whicii either proccelia com- 

 municates with the mesal series of cceliie ; (B) the two lateral orifices together with the 

 intervening space ; (Cj tlie mesal (cephalic) orifice of the diacoelia. We have been unable 

 to ascertain by whom the phrase was first employed, and the description by Monro secun- 

 dus (A, 12-16), in whose honor it was applied, is somewhat vague (Wilder, .5). 



(3) In order to indicate our opinion of the desirability of recognizing the aula as mor- 

 phologically an important element of the coelian series. 



§ 1066. Tel(B and Plexuses. — The atrophied or membranous roofs of certain coelise are 

 called tela vasculosa or tela choroidea, superior, inferior, etc., and the vascular plexuses 

 formed by them are designated as plexus choroideus ventriculi tertii, etc. If once the 

 general names for the encephalic segments and ccelise are adopted, we have only to employ 

 the characteristic prefixes and gain the single and definite names metutela, dintela, aula- 

 tela, metaplexus, diaplexus, auliplexus, portiplexus and proplexus. 



% 1067. CoinnmsurtB. — Of the bands of fibers, or aggregations of cells and fibers, by 

 which the parts of the brain — especially corresponding parts upon the two sides — are con- 

 nected, some are called commissures, while others have received special names. These 

 latter — callosum, fornix, pons and chiasma — are retained, but the other three — as proposed 

 by the senior author (it, 126, 14, 538) — are here simplified by prefixing to the word com- 

 missura the syllables prce. post and medi. 



§ 1068. Tabular- View of the Encephalic Segments and their ixirts in the Amphibian 

 Brain. — The accompanying Table contains the names of the principal parts of the brains 

 of the frog and Menobrauchus arranged according to the segments which they constitute 

 (Fig. 110-112). Attention is called to the recurrence of the prefixes clmracterizing the seg- 

 ments in the names of the corresponding caelim, telm and plexuses (§ 1066). A somewhat 

 similar table is given by Mihalkovics (A, 48), including also the names of the parts of the 

 mammalian brain ; see also Quain (A, II, 755). 



The abbreviation az. indicates that the part is azygous or unpaired ; the rest are lateral 

 and paired. 



