76 ORIGINAL ARTICLES. 



Thus, every original authority testifies that the presence of a third 

 lobe in the cerebral hemisphere is not " peculiar to the genus Homo," 

 but that the same structure is discoverable in all the true Simiae among 

 the Quadrumana, and is even observable in some lower Mammalia ; and 

 any one who chooses to take the trouble to dissect a monkey's brain, 01; 

 even to examine a vertically bisected skull of any of the true Simise, 

 may convince himself, on the still better authority of nature, not only 

 that the third lobe exists, but that it extends to the posterior edge of, if 

 not behind the cerebellum. 



2. The posterior cornu. — In the " Icones," already referred to, Tiede- 

 mann not only described but figured the posterior cornu of the lateral 

 ventricle in the Simia (Tab. 2°, Fig. 3 a ), as " e. scrobiculus parvus loco 

 cornu posterioris ;" and when giving an account of the brain of the seal 

 (Tab. 3 a ), he says: " e. cornu descendens s. medium. Prseterea cornu 

 posterioris vestigium occurrit." 



Tiedemann's statements are confirmed by every authoritative writer 

 since his time. According to Cuvier* (Lecons, T. iii., p. 103), " the an- 

 terior or lateral ventricles possess a digital cavity [posterior cornu] only in 

 man and the apes. This part exists in no other mammifer. Its presence 

 depends on that of the posterior lobes. In the seals and dolphins alone, 

 in which the posterior part of the hemisphere is considerable, the lateral 

 ventricle, at the point where it descends into the temporal tuberosity, 

 bends a little backwards, thus exhibiting a sort of vestige of the digital 

 cavity of the human brain. " 



Yrolik (Art. Quadrumana, Todd's Cyclopaedia), though he carefully 

 enumerates the differences observable between the brains of the Quadru- 

 mana and that of man, does not think of asserting the absence of the 

 posterior cornu. And lastly, Schroeder van der Kolk and Vrolik (op. 

 cit., p. 271), though they particularly note that "the lateral ventricle 

 is distinguished from that of man by the very defective proportions of 

 the posterior cornu, wherein only a stripe is visible as an indication of 

 the hippocampus minor;" yet the figure 4 in their second Plate shows 

 that this posterior cornu is a perfectly distinct and unmistakeable struc- 

 ture, quite as large as it often is in man. It is the more remarkable 

 that Professor Owen should have overlooked the explicit statement and 

 figure of these authors, as it is quite obvious, on comparison of the 

 figures, that his wood-cut of the brain of a Chimpanzee (1. c, p. 19), is 

 a reduced copy of the second figure of Messrs. Schroeder van der Kolk 

 and Vrolik' s first Plate. 



As M. Gratiolet (1. c, p. 18), however, is careful to remark, " unfor- 

 tunately the brain which they have taken as a model was greatly altered 

 (profondement affraisse), whence the general form of the brain is given 

 in these plates in a manner which is altogether incorrect." Indeed, it 

 is perfectly obvious, from a comparison of a section of the skull of the 

 Chimpanzee with these figures, that such is the case ; and it is greatly to 



Leuret, Longet, and Stannius, agree with or, perhaps, only repeat Cuvier. 



