No. 492] NOTES AND LITERATURE 



805 



ing account is given of the methods used in cutting sections of the 

 petrified trunks. Tubular drills were employed to cut out solid cores 

 for studying fruits, etc. These cores were then sectioned in the desired 

 directions. In this way the trunks could be fairly well preserved. 



Chapter four is concerned with the structure of the trunk, both the 

 external layer, which is mainly composed of large, closely packed 

 scales, "ramentum," and the internal structure, which is often pre- 

 served in a very perfect way and makes the structure of the trunks 

 perfectly <'lear. For details the reader nnist be referred to the memoir 

 The leaves of tiie fossil cycads have been preserved in many instances 

 in a remarkably perfect manner, even the young unfolded leaves being 

 clearly evident in some s[)ecimens. This is particularly the case in 

 one species, Cycadeoidm iru/rns. The yoimg leaves were ai)parently 

 quite similar to those of Dioon or Macrozamia. As is the case witii 

 the stem, the internal structure of the leaves is also ])erfe( tly pn^serA cd. 



It is the reproductive parts of these fossil cycads, ho^^cvcr, that are 

 of the greatest interest. While some of these are of th(> same tvpe as 

 those of the living cycads, one group, sometimes separatc-d from the 

 true cycads as a special order, Bcnnittitiales, had bisjxu-aiigiatc cones, 

 which apparently were curiously like the flowers of certain aiiizio^pcnns. 

 Some of these have been preserved in a wonderfullv pcrkvt niaimrr 

 owing to tlK^ young rouc^ l)<«ing comi)letelv protecte.l bv th<" annor ..f 

 scales in which they ^yvlv imbc<lded. The "flower"' consists of a 



numberof "synangia," cNtraordinarily like thoseof the fern MairaTtiju 

 Surrounding the wliole strobilus was a series of elongated scahvs or 

 bracts very much like th<^ floral envelopes of certain angiosperms. 



The type of cone shown in these Bennettiteae is much more special- 

 ized than that of the living cycads, but it is (luestionable whether the 

 resemblance to the angiospermous fU,wer is anvthing more than a 

 coincidence. X.-vertheh-s in the search for the ancestors of the pre- 



