186 ('. li. Wtdand — American Fossil Cyoads. 



point about one-third of the distance from the base to the kip 

 as reproduced in figures 2 and 4. Before taking up these, 

 however, it is highly desirable to briefly recall the several inter- 

 pretations of the Ci/caih (■((ltd testa. 



According to Carruthers' (1) original study given forty years 

 ago : 



"In liciiiu Kites Gibsonianus . . . Two envelopes enclose the 

 albumen and embryo. The outer envelope or testa, consists of a 

 thin layer of delicate elongated cells ; the inner is composed of a 

 single layer of oblong cells arranged with the longest diameter at 

 ri<*lit angles to the walls, and indurated by a considerable amount 

 of secondary deposits. . . . two coverings were produced 

 upwards into a tubular exostome or styliform process . . . 

 spread out like a stigma in the upper surface of the pericarp." 



In this description and illustration of the general features of 

 the seed the layer of collapsed fleshy cells immediately beneat'h 

 the indurated layer is not mentioned, Carruthers then going 

 on to say that, 



"Enclosed by these envelopes is the nucleus with its mem- 

 branous covering and abundant albumen . . . the subrectangular 

 cells of which are obvious in several seeds. . . . The albumen 

 was solid behind the embryo but was divided from top to 

 bottom down its center, in front of the embryo." 



Here we have unmistakably clear allusion to embryonic 

 features and tissue ; for the supposedly albuminous " subrec- 

 tangular cells" are simply the cotyledonary epidermis and 

 mesophyll, uniform in appearance and peculiarities of preserva- 

 tion, in the embryos of Bennettites Gibsonianus, B. Morierei 

 and several American specimens, all known in satisfactory detail. 



In the next description of these cycad seeds, that of Solms- 

 Laubach (1S90), the embryos were, however, clearly recog- 

 nized, and the testal structure described as follows : 



"Three distinct testal regions are to be noted, a basal, middle 

 and apical. 



" In the middle region of the seed the testa is closely appressed 

 to the nucular membrane, and wherever well conserved three 

 distinct layers may be recognized, the middle layer of which is 

 simply a single stratum of short prismatic palisaded thick- 

 walled, dark-brown cells; while the inner and outer layers con- 

 sist in several thicknesses of rather small thin-walled tissue. 



" The tissue of the inner layer is mostly crushed and indistinct, 

 while that of the outer layer appears as a light area following 

 the palisade layer, and finally passes over into more or less dis- 

 tinctly confluent growth with the walls of the seed cavity. At 

 least a distinct boundary appears but discontinuously. . . . 



