No. 2.] THE RELATIONS OF PROTOCERAS. 359 



can be made with certainty only when the phyletic series has 

 been worked out, and here, as elsewhere, any classification 

 which is made without knowledge of the various phyletic 

 steps, can be only temporary and tentative. 



In the case of Protoceras we may hope, with the complete 

 information as to its structure which we possess, to establish 

 its relationship to the Pecora as a whole with reasonable proba- 

 bility, the main outlines of the latter's phylogeny having been 

 fairly well determined. We shall need to remember Osborn's 

 dictum in this discussion, that " no case of exact parallelism 

 in both teeth and feet between two unrelated types has yet 

 been found, or is likely to be." (No. 7, p. 383.) If the Euro- 

 pean palaeontologists, beginning with Kowalevsky, are right, 

 then the ancestral form of the modern Pecora is the Oligocene 

 genus, Gelocus, and no fact is known which in any way impugns 

 the probability of this conclusion. The first step in our inquiry 

 must therefore be to institute a comparison between Geloc7is 

 and Protoceras. If the latter be referable to the Pecora at all, 

 it must be derived from Gelocus, which there is good reason to 

 regard as ancestral to that entire group. 



So far as the dentition is concerned, there is no very essential 

 difference between the two genera, but the European form has 

 molars in a less advanced stage of development, as is to be 

 seen in the thicker, more conical, and less completely cres- 

 centic form of the lobes. The premolars are likewise less 

 differentiated. The upper canine is compressed and blade- 

 like, while in Protoceras it is trihedral and opposes the first 

 lower premolar. The skull of the American genus is in many 

 respects much more modernized than that of Gelocus, though 

 the latter is only imperfectly known. Kowalevsky says of it : 

 " Leider habe ich in alien untersuchten Sammlungen keinen 

 completen Schadel finden konnen. Indess aus verschiedenen 

 Bruchstucken des Schadels geht unzweifelhaft hervor, dass 

 Gelocus weder geweihartige Auswiichse, noch Horner auf den 

 Stirnbeinen besass. Dieselben Bruchstiicke haben gezeigt, 

 dass die eigentliche Hirnkapsel nicht so weit nach hinten ver- 

 drangt war, wie es bei den heutigen Wiederkauern der Fall ist, 

 sondern eine mehr normale Stellung einnahm, in der Weise, 



