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BULLETIN 36, UNITED STATES NATIONAL MUSEUM. 



really separated tliej' have yet, as Professor Flower lias already said, 

 to be detected. 



Ill I), marginatns, Tiicberaii, we Lave for the first time in this geuiis 

 an instance in which both the external and osteological characters are 

 known. We are fortunate enough to have also complete data regard- 

 ing- three individuals of a closely allied species, P. plagiodon, Cope, and 

 are able to point out the distinctions between the two species very 

 satisfactorily (see p. 07). As regards the skull of P. marginaUis, it so 

 very closely resembles that of P. euplirosyne, both iu size, proportions, 

 and details of structure, that I am unable to find any ground for the 

 separation of the species. Professor Flower and Dr. Fischer both ad- 

 vance the same opinion, though with some hesitation. 



Clymene dorides and Clymenia euplirosynoides, Gray. 



Tlie type-skulls of these two species are of the same absolute length 

 and exhibit the closest agreement in the relative proportions of parts. 

 ISTo one who has examined them side by side, can, I think, doubt that 

 they represent the same species. They are smaller than the type of i'. 

 euphrosyne, but agree with that skull in proportions and details of 

 structure. C. euplirosynoides was not described by Gray, and the name 

 has therefore uo validity except for those who hold that reference to a 

 figure answers in the place of a description. 



Table of measurements. 

 PEODELPHINUS EUPHEOSTXE. 



