Herrick, Bmin of Certain Reptiles. 87 



and there produce their nerve-fibres which connect at suitable 

 levels with others. The fibres which spring from one end may 

 be many times longer than those fi-om the other (for the neuron 

 is primarily bi-polar), but it is indubitable that both may convey 

 stimuli. 



Transeetion of the ccrehniui of the PJirynosoma. (Plate V.) 

 Topographically considered there are few points of especial in- 

 terest in this brain that have not already been alluded to. Fig. 

 I cuts the right olfactory tuber near its base. The tuber has 

 already been described.^ Its ventricle is very small. The left 

 hemisphere is cut where it joins the rhinencephalon. The fibres 

 of the radix lateralis accumulate laterally. 



In Fig. 2 the rhinencoel has expanded into the ventro-ce- 

 phalic cornu of the ventricle and the latter communicates with a 

 large sickle-shaped dorsal cornu. It will be observed that in 

 this and other sections a sharply marked fissure on the mesal 

 aspect, corresponding to a furrow of the ventricle opposite it, 

 nearly separates the cortical from the basal part of the mesal 

 wall. 



In Fig. J the projection of the central lobe (striatum sensn 

 stiictu) forms a large part of the section. The cortex is differen- 

 tiated as already described in the lizard. That portion which 

 lies dorsad of the fissure of the mesal cortex above referred to 

 was called by me " fronto-median lobe" and its structure is 

 fully described on p. 18 of this Journal for March, 1891. See 

 X, Fig. 5. Laterad from this lobe there is a smaller portion of 

 cortex which caps the front of the brain and is occupied, 

 like the parieto-frontal lobe which clothes the lateral parts of the 

 free cortex, by pyramidal cells or at least a variety distinctly 

 different from the remaining regions. These two areas may be 

 located upon Fig. 5, the one mesad, the other laterad of the ref- 

 erence line passing to the hippocampal commissure. 



We still unhesitatingly adhere to our belief that these cen- 

 tres along the frontal and fronto-parietal aspects of the cortex 



1 It should have been added that the tuber is exceedingly produced in the 

 adult, being, in fact, as long as the entire prosencephalon and cylindrical and 

 slender throughout. 



