150 MAMMALIA. 



There are two in the European seas, viz.,— the Great Rorqual (Bat. boops, Lin.),— superior in length to the com- 

 mon Whale, and slmnned on account of its extreme ferocity, and the small quantity of its oil ; and the Stjiull Ror- 

 Cjual {BiU. mii.srultis, Lin.), which differs from the other [in its very inferior size, in its proportions, and number 

 of vertebra:. There is a third in the southern seasj and also a distinct fossil species. 



On proceeding to determine the fixed analop^ics of the teeth tbrou^liout the different groups of ^Vrtm/H'7//(7, we 

 have arrived (^ince most of tlie foregoing- pages were stfreotiiped) at tlie conclusion, that no phict'iital nianimalian 

 has more than three pairs of incisors, or three pairs of true or persistent molars, (normally,) in either jaw ; all 

 seeming exceptions being reducible to this general proposition: \^hereas the Marsupials have normally four of 

 each, and some even five. By persistent molars, are intended those which are not preceded by milk-teeth. 



Following, then, the indications afforded by the structure of the molars, (which we conceive to furnish the most 

 available guide to sound classification,) we are next led to recognize two principal varieties of dentition among the 

 Placentalioy to one or the other of which every observed modification may be definitively referred. These two 

 varieties are characterisitic of a g;reat zoophagoiis type and a great phytophagous type. 



Where exceptions occur in the former instance, the amylaceous parts of vegetables, as fruits, seeds, and faii- 

 naceous bulbs or roots, are almost exclusively resorted to; and animal products are preferred to the compo.-^itiou 

 of the recent carcass iu those few exceptive cases whicb, in a trivial degree, affect the latter generalization. 



Tbe zoophagous type of dentition is obviously of a higher grade than the other, and the animals in which it 

 occurs require more nutritious aliment. 



Throughout the zoophagous division, the molars are compact in texture, and tbe enamel never dips into thtir 

 substance; the basal growth of the teeth (except the pseudo-incisive canines only, in the very singular genus 

 Cheiromjis,) ceases upon the hdter attaining their required size; in consequence of which they gradually wear 

 down by attrition, till in aged animals they are not unfrequently reduced to stumps. 



In the )>lnit(iphagoiis division, the molars are much less compact, and the enamel generally dips into 

 their sut»stiince in various ways; the teeth are commonly furnished with persistent formative pulps, which 

 deposit fresh substance at their base as their crowns wear away, so that they continue permanently growing. The 

 exceptions that occur to this general definition do not intrinsically aftect the distinctness of the present group 

 from the other, and are easily understood, so that a transverse section of a molar il^nown to be that of a plaeojital 

 animal) will suffice in every instance for the determination to which it belongs. 



These two great divisions somewhat analogously subdivide each into two sections, which dilTer considerably in 

 the general details of their organization, and most commonly in the structure of the teeth. They may be regarded 

 as normal and abnormal sections. 



In the normal sections of the zoophagous and phytophagous grand divisions of P/a-ccnfa/in, the four sorts of 

 teeth — incisors, canines, renewed and persistent molars — are generally present, or at least three sorts of tlum, 

 each characterized by a particular form and structure different from the rest. In the abnormal sections, the teeth 

 are commonly much more numerous, and alike in structure, and consist principally or even wholly of false 

 molars; all of them are without exception single-rooted. 



We might consider these four sections as Orders, and denominate them as fohow. 



A. Zooj'liaffOKS type. 



1. Ti/po(loiitia. Nonnal : comprehending the Bimana, Qnadrumona, and Camass'icrs of Cnvier. 



2. Lsudijnl'ia. AbnoiTual : consisting of the C'ftact'a of Cuvier, divested of the herbivorous sulnlivision. 



B. Phiitiijibaiious type. 



3. Diplodontia. Normal : comprising the Paclni'lcnnaln, Cc/acea hcrhh-ora, Rodcntia, and Rnmi/tanlm of 

 the same naturalist. 



4. Aplodonfia. Abnormal : corresponding to tbe Edentata of Cuvier, divested of the Moiudn-mata, 



These together constitute the Hormcv/ or placental subclass of Mfunn/alui ; ami Uic ab/ivrinid ur ovo-viviparous 

 subclass might range in two orders only, viz. : 



5. Heierodonfia. Normal: or i'h^ Marsiipiato-: and 

 C. Pseudodont'ia. Abnormal: or Vne, Monofremal a. 



The Typodontia primarily subdivide into the Primates and Fert^e of Linna-us, or Sccnndatcs^ as the latter has 

 recently been termed by De Blainville. 



Tbe Primates are characterized by the external distinctions popularly known, and also, it nuiy l.'C added, by tbcir 

 hair being of one sort only, having never any softer felt beneath it.* They separate into Cheiropoda and Vhcirojdcra. 



The Clieiropoda comprise the Bimana and Qnadrumona of Cuvier, but not the marsupial handed animals, in- 

 cluded under this name by Mr. Ogilby. They have never more than four incisors in either jaw, invariably pos- 

 sess a ccecum, have no os penis, and are bom with the eyes open. They subdivide into Anfhropida a.n<i Lemuria. 



The Anthropida are characterized by the general form of the head, the complete separation of the orbits from 

 the temporal fossa by a bony partition, by having the incisors broad and contiguous, and vertical, or nearly so, 

 in both jaws, by their anthropoid molars, Sec. Their teeth form an even series, the continuity of which is only 

 broken by the interspace required for the reception of the opposite canine; and in I\Ian only, where the canines 

 are not lengthened beyond the other teeth, even this vacuity does not occur. They fall into the Catarrhi/ii and 

 Ptafyrrhini of Geoffroy, according to the number oi false molars; and the circumstance of their being respectively 

 peculiar to the Old and New W^orlds, affords a presumptive argument that the human genus, which pertains 

 strictly to the former, is not indigenous to Amei'ica. 



* W'li wuru deceived by certain .ijipcaraiicci Ui staling Lh.^t c.^ceptifins to this ruic csistcd, nt pp. 57. ItO. 



