472 Rerieics — Prof. Copers Extinct Vertebrates of iV. America. 



Platy cheer ops. The author thinks that this genus may be regarded 

 as an ancestral form of the Erinaceidee. The upper molars and 

 the hinder premolars are triangular in form, and of equal com- 

 plexity. In the family Miacidae we have several genera, among 

 which we may mention Miacis and Didimictis ; this family Prof. 

 Cope regards as making the nearest approach to the modern Carni- 

 vora Vera, the lower jaw being furnished with a true " carnassial" 

 tooth. This approximation fully confirms our own view as to the 

 impossibility of satisfactorily distinguishing the so-called Creodonta 

 from the Carnivora Vera on the one side and the Insectivora on the 

 other. 



The Lemuroidea and the Insectivora. — In this memoir the author 

 says that it appears impossible to draw any satisfactory distinction on 

 the evidence of the skulls and teeth alone between the two groups 

 mentioned — the latter including, it may be presumed, only those 

 forms which the author does not class in his Creodonta. This con- 

 fession appears to us to be another argument against the acceptance 

 of the author's order Bunotheria (of which the Insectivora, as 

 restricted by him, form a suborder) ; the retention of which appears 

 to us merely to obscure the relations of its different members. In 

 reference to Prof. Cope's so-called Hyopsodus vicariiis, — this is 

 a genus which in a paper read before the Geological Society on 

 June 24th has been shown to be probably identical with the 

 English Upper Eocene genus Microchoerus, whose affinities appear to 

 be decidedly Insectivorine. Lower jaws of the genera Notharctos 

 and Tomitherium are figured, and appear to indicate forms allied to 

 the Lem urine Necrolemiir and Adapis. A genus represented by species 

 of small size, and named Anaptomorphus, is considered to be allied to 

 the existingLemurine Tarsufs of Java. In the Insectivora Prof. Cope in- 

 cludes the European Eocene genus Arctocyon,ou account of the form of 

 its molars, and also classes in the same family the American Achos- 

 nodon. With regard to the former we are fain to confess that its 

 affinities seem so generalized that it appears to us to be impossible to 

 assign it any very definite position, and we should have preferred to 

 have placed it among the primitive Carnivores without indicating its 

 relationship too closely. When, indeed, we reflect how very diffi- 

 cult it has been to assign living forms like Chiromys and Galeopi- 

 thecus, where we have the whole animal before us, to their proper 

 serial position, it surely cannot be expected that we can in all cases 

 refer fossil mammals to a definite position when at the best we have 

 only more or less perfect portions of the skeleton to guide us. Achce- 

 nodon appears to us to be a form not improbably connecting the buno- 

 dont ungulates like Elotherium (with which it has been classed) with 

 the unguiculate mammals ; its affinity to the latter being indicated 

 by the nature of the articulation of the lower jaw. We totally fail 

 however, to see why it should be categorically referred to the Insec- 

 tivora. 



The Tertiary MarsupiaUa. — Our author divides the extinct Mar- 

 supials into the trituberculate, quadrituberculate, and multitubercu- 



