142 ('. It. Wieland — American .Fossil Cycads. 



text figures '2, 4, from the equatorial region of the seed. 

 These include all the best known forms, the seeds of Oycad- 

 ,<>,',/,(( dacotnisis and of (\ e.rcelsa and Jenneijana excepted, 

 as these have not so far been found well enough conserved to 

 permit such drawings; though it can be seen from their gen- 

 eral form and amount of testal development, which are well 

 known, that they too agree within generic limits. 



In comparing these drawings it must always be remembered 

 that the seed wall is a more or less appressed one, as the result 

 of enclosure by the five or six to as many as eight or ten inter- 

 seminal scales forming the pocket in which the seed lies. Also 

 both outer flesh and stone normally thicken markedly toward 

 the shoulder and about the basal region of the micropylar tube 

 to form a ribbed or even-tentacled corona. But while these 

 coronal ribs may tend to disappear in some species, pr may 

 somewhat conform to surrounding scales, an original and 

 fixed number is in reality alioays present and representative 

 of the species. Furthermore the ribs may even send up a low 

 crown of tentaclelike projections about the base of the 

 micropylar tube, though it is only after studying the sections 

 very attentively that one comes to see this feature, which, 

 could one see a loose seed, would be very distinctive indeed. 

 In short, we have to do with somewhat appressed vestigial lobes 

 as unmistakable as those of Physostoma. 



Lateral Testal Envelopes. — As already observed the " en- 

 veloppe tubuleuse " of Lignier, or cup-like husk formed b} 7 the 

 extension of the cortex of the seed pedicels all round the seed 

 base, tends to disappear. The really complex structure of this 

 envelope has been conserved with diagrammatic clearness in 

 B. Morierei, where it is clearly seen to consist in an under- 

 layer, the " assize plissee" really the base of the "blow off," 

 and a distinctly tubular outer layer which is not found continuous 

 all over the surface of the seed, though its cells are markedly 

 susceptible of preservation. But in strong contrast and clearly 

 proving reduction, fig. 4A is an accurate enough drawing of an 

 American seed in which too few tubular cells to show appear 

 to rest on the middle stone, while there is no appreciable pre- 

 servation of the inner part or " assize plissee " and its apical 

 continuation as a strongly palisaded tissue, "assize rayonante''' 1 

 or " blow off." This condition is, however, exceptional, but 

 one species showing so much reduction. 



Once more in examining transverse sections of American 

 species a doubt may arise as to whether the outer layer of the 

 seed is not actually confluent with the interseminal scales as 

 Solms supposed it might be in places (" Stellenweise ") in 

 Bennettites Gibsonianus. But this, it is thought, may be due 

 in part to the fact that there are in the interseminal scales 



