208 F. W. Very— On the Solar Constant. 



emission of the same waves by the lower layers, whereas the 

 hypothetical equation with exponent 4 requires such emission. 

 This part of the subject is still very obscure. 



In conclusion, it seems to me that the bolographic argument 

 for a value of the solar constant approaching 4 calories is 

 sound, but the primary pyrheliometric reduction employed by 

 Bigelow involves the same erroneous assumption of a constant 

 diurnal coefficient of transmission which has vitiated the work 

 of Pouillet and of Abbot ; while the doubling of the value 

 given by this primary or preliminary reduction, although in 

 approximate agreement with what may be obtained by means 

 of a rational theory, is in the present instance a completely 

 arbitrary procedure. 



Westwood Astrophysical Observatory, 



Westwood, Massachusetts. October, 1914. 



Art. XIV. — An Eocene Ancestor of the Zapodilla • by E. "W". 

 Berry. With Plate I. 



I have had in my possession for several years a large fossil 

 seed collected by Mr. A. F. Crider from the Upper Claiborne 

 deposits (middle Eocene) of Holmes County, Mississippi, which 

 in the press of other duties remained undetermined until the 

 recent appearance of a paper by Mr. Henry Pittier* led me 

 to compare it with the seeds of the Sapotacese, more especially 

 those of the large-fruited genera Achras, Vitellaria, Lucuma, 

 Calocarpum, etc. 



The fossil seed, while it has the general characters of the 

 seeds of the genera enumerated above, is not exactly like any 

 of them. In size and form it is perhaps most like the seeds 

 of Achras but in the latter the umbilical area is narrow and 

 shortened, while in the fossil this area is the full length of the 

 seed and wide as in the genus Calocarjpum. A real difficulty 

 encountered in giving a name to the fossil arises, not out of 

 any uncertainty with regard to its relationship to still existing 

 forms, but out of the purely taxonomic tangle that involves 

 these forms and a lack of knowledge regarding the relationship 

 of these among themselves and their true generic limits. 



For example, Achras is a monotypic genus in the existing 

 flora, artificially distributed in prehistoric times and now 

 cultivated in all tropical countries. Its single species has 

 served as the type of at least two genera, i. e. Achras Linne 



*Pittier, H., Cont. U. S. Natl. Herbarium, vol. xviii, part 2, pp. 76-86, 

 1914. See also Cook, 0. F., ibidem, vol. xvi, pp. 279-282, 1913. 



