358 SCOTT. [Vol. XI. 



question rather an open one. " If now we compare Protoceras 

 with any family of the Pecora, there are so many striking dif- 

 ferences at once apparent that we are compelled to conclude 

 that there are no marked affinities in the direction of any of 

 these families. In the possession of bony protuberances on 

 the parietals, which are probably processes of this bone, and 

 not developed separately as in the Giraffe, in the general archi- 

 tecture of the skull, together with so many primitive characters 

 of the feet, this genus apparently occupies a distinct position 

 and cannot be consistently referred to either the Tragulina or 

 the Pecora as at present constituted and defined. The posses- 

 sion of multiple horns suggests the possible relationship of this 

 family to the Sivatheriidse, but the likeness does not extend to 

 other features of the skull." "That it \i.e., Protocej-as] repre- 

 sents a distinct family there can be little doubt. Of its suc- 

 cessors we know nothing whatever, and our ignorance is equally 

 great in the matter of its ancestry." (No. 8, p. 369.) 



Flower has well stated the difficulty of determining the rela- 

 tionships of artiodactyl groups, the ancestry of which can only 

 be conjectured. " The Pecora or true Ruminants form, as has 

 often been remarked, an extremely homogeneous group, one of 

 the best defined and closely united of any of the Mammalia. 

 But though the original or common type has never been de- 

 parted from in essentials, variation has been very active among 

 them within certain limits, and the great difficulty of subdi- 

 viding them into natural groups (*the despair of zoologists,' 

 as Pucheron calls it) arises from the fact that the changes in 

 different organs (feet, skull, frontal appendages, teeth, cutane- 

 ous glands, etc.) have proceeded with such apparent irregularity 

 and absence of correlation, that the various modifications of 

 these parts are most variously combined in different members 

 of the group." (No. 2, p. 181.) All this applies almost equally 

 well to the Artiodactyla as a whole, and the mutual relationships 

 of the various subdivisions which compose that order. This 

 difficulty proceeds from the frequent impossibility of deter- 

 mining what points of resemblance between the groups to be 

 compared are due to inheritance from a common ancestor, and 

 what are cases of parallel development. Such determination 



