1 (i8 P>''>f- Don's Descriptions of two new Genera of the 



tliat a braacli of the one might readily be iiiLstakeu for that of the other. The 

 leaves are evergreen, subulate, laterally comj)ressed, and in other respects they 

 closely resemble those of that plant. The structure of the reproductive organs is 

 even more remarkable tlian in any other of the Cupressinecc. The male catkins, 

 Avliich in the other genera of that group are terminal and solitary, are here 

 numerous, as in the normal tribe oi Pimis, and crowded in a spike-like man- 

 ner at the extremity of the branches. They are short, and the antheriferous 

 scales are crowded, sessile, and closely imbricated, as in ^-Jraucaria exceha and 

 Cttnninghaniil. The thecre, 5 in number, are unilocular, very short, condiined 

 together in a single series, concealed at the base of the scales, and open in- 

 wardly towards the axis by a large rounded aperture. The female spikes are 

 solitary and borne on the same tree, and most frequently on the same branch, 

 in which case they occur on the inferior branchlets. They are globular, 

 squarrose. and about the size of a walnut. The most remarkable peculiarity 

 of the genus, however, is that the conqjosition of the male inflorescence seems 

 to be reproduced in the female, the pericarpium apparently consisting of a 

 verticil of leaves combined together, and concrete with the bracte, which is 

 here much develoi)ed ; the points of the jjcricarpial leaves, together with the 

 up])er portion of the bracte, are free, and crown the mature fruit in the form 

 of subulate recurved teeth. The ovula vary from 4 to 5, and ap[)ear to bear 

 some relation to the divisions of tiie pericarpium by which they are concealed. 

 The more complex structure of this genus appears to militate against the view 

 taken by Dr. Schleiden of the female flower of Ahiet'inece in his interesting 

 memoir on the vegetable ovulum, of which a translation is given in that valu- 

 able periodical, the " Philosophical Magazine and Journal of Science," for 

 FebruaiT and March last. According to him, the ovula in all cases originate 

 from the axis, of which the placenta is a motlified portion ; and he regards the 

 scale, or what I have described as an expanded pericarpium, in Jhietineœ, as, 

 in realitv, the placenta, and what has hitherto been regarded as the bracte as 

 the true pericarpial leaf. This opinion he founds upon an examination of a 

 monstrous spike of Jhies alba, which upon the upper half bore female, and 

 upon the lower half male, flowers, and he refers to an unpublished work of his 

 for further details, ^^'ith the very brief notice given in the memoir above- 

 mentioned, and in the absence of the proofs which are to be adduced by 



