Variations of the dog cerebral sulci, compared in particular with those of the cat

Various types of 15 sulci, ill on the lateral and 4 on the medial surface, of the dog cerebral hemisphere, were examined. Each sulcus has several formes and a sulcal pattern which shows the highest frequency is taken as a "standard" type. A standard map of the dog brain is presented based upon the present observation. Sulcal patterns of the dog cerebrum are in general as consistent as those of the cat brain. However, some sulci, i.e., a small branch of the suprasylvian sulcus, the suprasplenial and postsplenial sulci, the ectolateral, the genual, the prorean, and the eetosylvian sulcus, show variety of formes. Variations of the dog sulci are discussed and compared with those of the cat. The comparison shows that the sulcal patterns which appear only in the dog are on the whole most variable.