HYPERTROPHIED LEAVES. 49 



lar to the type of leaf seen in Pseiidotsiiga, and in many species 

 of Abies, and to this extent we would seem to be warranted in 

 saying that the Pines have been derived from a generalized 

 form having a leaf and other characters midway between the 

 firs and spruces. The nearest living representative of such a 

 form is Pscudotsiiga. As regards the strobile, while pendant 

 and spruce-like in certain characters, especially when young, in 

 its large scales it is fir-like. As regards the leaves, it is decidedly 

 fir-like. As to general habit, it is spruce-like. 



There is another value to be attached to this comparison be- 

 tween abnormal leaf and true primary leaf Their close corre- 

 spondence in structure supports Celakovsky's view that abnor- 

 malities in the Conifers are of very great value as a basis for 

 morphological study. 



It has been said earlier in this paper that we have in these 

 abnormal leaves a retrogression to ancestral types. If this be 

 so we should look for a condition in the more immediate an- 

 cestral forms of the pines in which the primary leaves are nor- 

 mal, and later, intermediate forms should show a gradual sub- 

 stitution of fasciculated leaves for scattered ones. 



Now there have been found in the Jura of eastern Siberia 

 certain forms which were described by Heer^ under the generic 

 name of Leptostrobiis. The description was originally based 

 upon the cones only. Further material was afterwards obtained 

 which showed the leaves to be pine-like and apparently fascicu- 

 lated at the ends of the short twigs. The material was, how- 

 ever, meagre, and nothing further was made out in regard to 

 the arrangement of the leaves. 



Later Fontaine found in the Potomac of the Eastern United 

 States forms evidently closely allied to Heer's Leptostrobiis. 

 These he described^ under Leptostrobiis, taking the precaution, 

 however, of extending the original description by the addition 

 of the following remark bearing on the position of leaves 

 "leaves . . . scattered on the larger or principal stems and 

 grouped in bundles on the ends of short twigs." This was a 



1 Flor. Foss. Arctica, VI : 23, 



2 U. S. Geol. Survey, Monograf XV. 



Annals N. Y. Acad. Sci., XI, April 20, 1898 — 4. 



