J. M. Clarke — Clymenia in Western New York. 57 



and 1200° respectively, the latter being very near the melting 

 point. 



Combining the present series I with the former series III, 

 I obtain for the relation of melting point and pressure, dT/dp, 

 at 1200°, since T=1470°, <r—r= -0394/2-72, r'=24, dT/dp= 

 •021; and at 1100°, since T=1370°, a-z= -0385/2-72, r = 16, 

 dT/dp='029. Similarly combining the present series II with 

 the former series IV, at 1200°, since a-z= -0352/2-72, r'=24, 

 dT/dp= 019 ; and at 1100°, since a-x= -0341/2-72 and r'=l§, 

 dT/dp='026. 



Hence the probable silicate value of dT/dp= m 025 at 1170°, 

 falls nicely within the margin (-020 to -036) of corresponding 

 data for organic substances (wax, spermaceti, paraffin, naphtha- 

 lin, thymol). I may therefore infer that the relation of melt- 

 ing point to pressure in case of the normal type of fusion, is 

 nearly constant, irrespective of the substance operated on, and 

 in spite of enormous differences of thermal expansibility and 

 (probably) of compressibility. A portion, in a given substance 

 changed only as to temperature and pressure, the relation of 

 melting point and pressure is linear. 



The immediate bearing of all of this on Mr. Clarence King's 

 geological hypothesis is now ripe for enunciation. 



Aet. YIII. — The discovery of Clymenia in the Fauna of 

 the Intumescenszone {Naples beds) of Western New York, 

 and its Geological Significance', by John M. Clarke. 



The ammonoid genus Clymenia Minister, has not hereto- 

 fore been found in North America. As early, however, as 

 1843, Professor Hall doubtfully referred* to this genus, a 

 fossil from the Portage shales, the Clymenia f complanata, 

 and in 1862f re-described the species without the mark of 

 doubt, at the same time adding a new specific name, C. Erato, 

 for a fossil from the same fauna. Subsequently these fossils 

 were proved to be of the same species, and though the name 

 Clymenia was still retained as late as 1876,^; it was finally and 

 quite properly abandoned in 1879.§ 



The present discovery of a true Clymenia in a lower Upper 

 Devonian fauna containing Ooniatites intumescens and various 

 other primordial goniatites, was unexpected and is of consider- 

 able geological importance. 



* Geology of New York, Report of the Fourth District, p. 244. 

 \ Fifteenth Ann. Rept. X. Y. State Cab. Nat. Hist., pp. 63, 64. 

 1 Illustrations of Devonian Fossils, expl pi. 70, figs. 6-11. 

 § Palaeontology of New York, vol. v, pt. 2, p. 455. 



