THE PLACOID BRAIK 137 



This affiliation has a special support in the brain of the dol- 

 phin family, which is distinctly allowed to be, in proportion 

 to general bulk, the greatest among mammalia next to the 

 ourang-outang and man. We learn from Tiedemann, that each 

 of the cerebral hemispheres is composed, as in man and the 

 monkey tribe, of three lobes, — an anterior, a middle, and a 

 posterior ; and these hemispheres present much more nume- 

 rous circumvolutions and grooves than those of any other 

 animal. Here it might be rash to found anything upon tne 

 ancient accounts of the dolphin, — ^its familiarity with man, 

 an4 its helping him in shipwreck and various marine disas- 

 ters ; although it is difficult to believe these stories to be al- 

 together without some basis in fact. There is no doubt, how- 

 ever, that the dolphin evinces a predilection for human society, 

 and charms the mariner by the gambols which it performs 

 beside his vessel" 



Here, then, the author of the "Yestiges" palpably founds 

 on a large development of brain in the dolphin, and on the 

 manifestation of a correspondingly high order of instincts ; 

 and this altogether irrespective of the structure or composi- 

 tion of the creature's internal skeleton. The substance to 

 which he looks as all-important in the case is brain, not bone. 

 For were he to estimate the standing of the dolphin, not by 

 its brain, but by its skeleton, he would have to assign to it 

 a place, not only not in advance of its brethren the mam- 

 malia of the sea, but even in the rear of the reptiles of the 

 sea, — ^the marine tortoises, or turtles, — and scarce more than 

 abreast of the osseous jQshes. " Fishes," says Professor Owen, 

 in his " Lectures on the Vertebrate Animals," " have the 

 least proportion of earthy matter in their bones ; birds the 

 largest. The mammalia, especially the active, predatory 

 bpecies, have more earth, or harder bones, than reptiles. In 

 each class, however, there are differences in the density of 

 bone among its several no embers. For example in the fresh- 



