I860.] Cerebral System of the Class Mammalia, 181 



section of the Mammalia. To associate the Ltencbpeala and L is sen- 

 CEi'HALA with the unguiculate GynENCEPHALA into one great primary 

 group, appeared to the speaker to be a misapplication of a solitary 

 character, akin to that which would have founded a primary division 

 on the discoid placenta or the diphyodont dentition. No one had 

 proposed to associate the unguiculate Bird or Lizard with the ungui- 

 culate Ape ; and it was but a little less violation of natural affinities 

 to associate the Monotremes with the Quadrumanes in the same pri- 

 mary (unguiculate) division of the Mammalian class. 



The three primary divisions of the Gtrencephala were of higher 

 value than the ordinal divisions of the Lissencephala ; just as those 

 orders were of higher value than the representative families of the 

 Ltencephala^ 



The Mutilata, or the maimed Mammals with folded brains, are so 

 called because their hind limbs seem as it were, to have been ampu- 

 tated ; they possess only the pectoral pair of limbs, and those in the 

 form of fins : the hind end of the trunk expands into a broad, horizon- 

 tally flattened, caudal fin. They have large brains with many and 

 deep convolutions, are naked, and have neither neck, scrotum, nor 

 external ears. 



The first order, called Cetacea, are either edentulous or mono- 

 phyodont, and the latter have teeth of one kind and usually of simple 

 form. They are ' testiconda,' and have no ' vesiculse seminales.' The 

 mammae are pudendal ; the placenta is diffused ; the kidneys are much 

 subdivided ; the arterial system is remarkable for vast and complex 

 * plexuses,* covering the spinal chord and lining the intercostal spaces, 

 forming a reservoir of arterial blood : the external nostrils — single or 

 double — are on the top of the head, and called spiracle or, blow- 

 holes.' They are marine, and, for the most part, range the wide 

 oceans ; though with certain geographical limits as respects spec" eg. 

 The ' right whale' of the northern hemisphere {Balcena mysticctus) 

 is represented by a distinct species (Balcena australis) in the southern 

 hemisphere : the high temperature of the waters at the equatorial zone 

 bars the migration of either from one pole to the other. True Cetacea 

 feed on fishes or marine animals. 



The second order, called Sirenia, have teeth of different kinds, 

 incisors which are preceded by milk-teeth, and molars with flattened 

 or ridged crowns, adapted for vegetable food. The nostrils are two, 

 situated at the upper part of the snout ; the lips are beset with stiff 

 bristles ; the mammae are pectoral ; they are ' testiconda,' but have 

 vesiculae seminales. The Sirenia exist near coasts or ascend large 

 rivers ; browsing on fuci, water plants, or the grass of the shore. 

 There is much in the organization of this order that indicates its nearer 

 affinity to members of the succeeding division, than to the cetaceous 

 order. The Dugongs (Halicore) inhabit the Red Sea, the Malayan 

 Archipelago, and the soundings of the Australian coasts ; the Manatees 

 (Manatus) frequent the shores of tropical America and Africa. 



In the Ungulata the four limbs are present, but that portion of the 

 Vol. III. (No. 31.) o 



