THE CRUCIATE FISSURE. 499 



its relation to the F. interhemispheralis. Its symmetry is also remarkable ; very rarely is 

 the mesal end on one side farther caudad than on the other. 



The mesal portion is less uniform. The caudal half often tends slightly dorsad and 

 the end is sometimes forked. Rarely does the caudal end join the F. splenialis. Accord- 

 ing to Krueg (2, 620), the union was observed once by Guillot (A, Fig. 172) ; Krueg him- 

 self has seen it only twice (2, 620), and Pansch (/, 21, Fig. 27) three times out of fourteen. 

 Out of about 400 hemispheres of adult cats dissected by us or our students or preserved 

 in the Museum of Cornell University and in the Museum of Comparative Zoology, it 

 was noticed in only 4. 



In view of Broca's idea (1) that the cruciata and splenialis are morphologically parts of 

 a single fissural integer, their relations should be carefully examined ; note should be 

 taken as to whether a junction is effected by means of branches or by a deflection of one 

 or both of the fissures themselves ; whether the combined fissure is shallower at the place 

 of junction, and whether the junction exists upon both hemispheres. 



This fissure is also interesting on account of the various opinions which have been 

 expressed as to its human homologue (see 1370), and because several well-marked 

 " motor centers " have been found about its dorsal portion ; apparently none have been 

 discovered upon the mesal surface of the hemisphere. 



1859. Formation. As intimated by the senior author (11, 226), and more distinctly 

 shown by Pansch (1, Fig. 32) and Krueg (2, Taf. XXXIV), the F. cruciata really begins 

 upon the mesal aspect of the hemisphere, as a shallow depression which gradually ap- 

 proaches the margin, indents it, and finally extends laterad for a distance equal to or 

 greater than its mesal part. Upon a series of kitten's brains, from a week before birth 

 to a week after, the formation of this fissure is beautifully illustrated. 



1360. The Name. Owen's "frontal " is descriptively significant, but it implies a not 

 yet proven homology with one of the human frontal fissures, and is antedated by Leuret's 

 " crucial." As to the technical form, there seems little to choose between crucialis and 

 cruciata. Personally we prefer the former, but Krueg has employed the latter, and his 

 name is here adopted. 



1361. Synonymy. The following synonymy is chronological, and intended to include 

 all the works and papers in which the cruciate fissure is mentioned. It forms part of an 

 unpublished paper by the senior author which is mentioned in 8, 49, and 14, 524. 



Cuvier (1805) ; " en avant, un sillon court qui la traverse en croix ; " Carnivora ; C, 

 II, 157. 



Owen (1833) : " a transverse anfractvosity the transverse anfractuosity the first trans- 

 verse fissure ; " cat, cheetah ; 35, 133, 134 ; PI. XX, " 1." 



Owen (1835) ; " the anterior transverse anfractuosity ; " Cercoleptes (kinkajou) ; 53, 

 122. 



Leuret (1839) ; ''sillon crucial ;" cat and the Carnivora generally ; Leuret et Gratio- 

 let, A, I, 379, etc., PI. V, Fig. 3, opposite " a." 



Cuvier, Dumeril, etc. (1845); " sillon crucial;" Felidae and most other Carnivora; 

 Cuvier, B, III, 93. 



Dareste (1855); "sillon crucial ;" cat and several other Carnivora; 13, 110, PI. II, 

 Fig. 1, 2, 4, 8, "/" 



Owen (1868) ; " the frontal fissure ; " cat and the " Gyrencephala " generally ; A, III, 

 116-136, Fig. 91, etc., " 14." 



Flower (1869) ; " crucial siilcus, crucial fissure ; " Proteles cristata and the Carnivora 

 generally ; 28, 479, 482, Fig. 1, 2, 4, " c." 



