THE BEAIN I^" THE EDENTATA. 311 



A sagittal sulcus (7) pursiics a course parallel to and at a distance of about 5 mm. from 

 the interhemispheral cleft for about the middle two fourths of the margin of the 

 hemisphere in our type-specimen. Just behind its caudal extremity there is another 

 short sulcus which probably belongs to the same series. In a second brain this sulcus 

 is also present in both hemispheres, but is interrupted and in parts very shallow on 

 the riglit side. In the third specimen the sagittal sulcus is represented in each 

 hemisphere merely by short sulci at the cephalic and caudal extremities of the position 

 which the sulcus Avould occupy. These short sulci are united by a very shallow furrow. 

 In Pouchct's and Forbes's illustratious continuous sagittal sulci are represented; while 

 in the cranial cast figured by Gervais deep coronal grooves are indicated, and each 

 apparently lodges a large blood-vessel. 



Just below the caudal extremity of the sagittal sulcus (y) there is in our type-specimen 

 a shallow, almost vertical sulcus, which probably corresponds to the sulcus in Ilurmeco- 

 fliacju. In one of the other two braios this sulcus is even more faintly marked still, but 

 in the third we find an exceedingly interesting condition. In this brain tliere are 

 indications of an arcuate sulcus resembling the suprasylvian sulcus in the Carnivora_ 

 A sulcus begins a short distance aljove the point of junction of the anterior and posterior 

 rhinal fissures, and after arching upward and backward for a short distance it passes 

 into a shallow furrow which ciu'ves backward and vertically downward in a situation 

 exactly analogous to the sulcus S in MyrmecoplicKja. It seems as though this represented 

 a more complete arcuate or siiprasi/Jvum sulcus than is present in Ilijrmecophaya. It 

 may be that the depression S' in the latter represents the cephalic extremity of the arc. 

 Upon the left hemisjihere of this l)rain of Tamanditu we find the uj^per part of the 

 arcuate sulcus without the descending part. 



The cranial cast of Tanmndua which Gervais has represented * is considerably larger 

 than any brain which I examined or of which there is any record. From this cast we 

 might gather that the sagittal (y) and supraorbital (/3) sulci were deeper and more 

 definitely maj)ped orit than they are in the brains we have examined. 



In the absence of any fossa Sylvii it would have been difficult to detect in the brain of 

 Tamandua any resemblance to the Carnivorous type of bi-ain, but 3Iij rmecopha ga provides 

 for us the needful connecting-link. For, while clearly exhibiting the family type which 

 binds it to Tamandua, it shows us how the Sylvian fissure becomes obliterated, so that 

 the transition from the Carnivorous to the simple Tamandua type is easy to follow. 



A notable demonstration of this resemblance is given by the developing l)raln of 

 Felis, which Krueg has figured f. At a ]3eriod just before the Sylvian fossa makes its 

 apjiearance, the configuration of the pallium of the foetal kitten presents a surprising 

 resemblance to the adult Tamandua, with its supraorbital (/3), sagittal (7), and suprasylvian 

 (g) sulci. 



At the same time Tamandua demonstrates the superiority of the Carnivore's brain 

 For in the latter order a brain of the dimensions of that of Tamandua would certainly 



* P. Gervais, op. ell. pi. ii. fig. 2. 



t Julius Krueg, op. (it., Zeitsch. f, wissensch. Zool. lid. xxxiii. Taf. sxxiv. 

 SECOND SERIES. — ZOOLOGY, VOL. VII. 47 



