PHILOSOPHICAL SOCIETY OP WASHINGTON. 135 



"showing for each year from 1760 to 1876, both inclusive, the 

 relative value of gold to silver in open market; also, the average 

 of these rates by periods of five years each ; and compared with 

 the standard mint ratio of the United States; also with that of 

 the Latin Union." 



He also made a communication on 



OPTIONAL MONETARY STANDARDS, 



referring to duplicate and triplicate standards, each alike author- 

 ized as legal tenders, and either of which may be used at the 

 option of debtors. 



Mr. Theodore Gill made a communication on 



THE MORPHOLOGY OP THE ANTLERS OF THE CERVID^. 



Incited by a recently published article by Prof. Garrod, of 

 London, on some points in the anatomy of the Ruminants {p'roc 

 Zool. Soc. London, 1877, pp. 1-18), the author had lately re- 

 investigated the mode of growth of the antlers of the deer. The 

 results finally reached may be summarized in the following defi- 

 nition of antlers : — 



Antlers are horn-like appendages of frontal processes, peculiar 

 to the deer, developed periodically and concomitantly with the 

 sexual organs, chiefly in the males, either as simple spikes or 

 with a tendency to .bifurcation, especially (hut not exclusively) 

 m the direction of the varying greatest or axial growth. 



The modifications of the antlers and their contiur in the vari- 

 ous forms of the family are chiefly dependent on and determined 

 by the diverse exhibitions of this tendency, and examples of 

 several kinds are furnished by the genera Pudua, Cervus, Ela- 

 phurus, and Cariacus. 



The branches into which the antlers successively divide in those 

 deer distinguishable by the complexity of those appendages may 

 be homologized with each other, and in the interests of a uniform 

 system of terminology the author proposed the following names 

 applicable to the chief subdivisions: (1) The simple spikes of 

 the first year and their after-growths were designated protoceres, 

 (2) the anterior ofi-shoots of the second year deuteroceres and the 

 succeeding (3) third, (4) fourth, and (5) fifth anterior offshoots, 



