XII. 



A NEW PART OF PACHYTHECA. 



A PAPER by Sir Joseph Hooker, in the Annals of Botany (vol. iii., 1889), 

 gives the history of this remarkable and very puzzling fossil from the 

 Devonian rocks, while a study of its structure by Mr. Barber will be found 

 in two papers, one in the volume cited, the other in vol. v. A note on the 

 subject by Mr. Thiselton-Dyer appeared also in the latter volume. The 

 most ample discussion of the subject has not left us with any clear idea of 

 what PacJiytJieca may be, and this is certainly the fault of the inadequate 

 nature of the evidence it presents rather than any lack of ingenuity on the 

 part of those who have sought to interpret it. The discovery of an addition 

 to this evidence in the form of a new part of the fossil therefore raised my 

 hopes greatly of finding some clue to its true character. I am bound to 

 confess at the outset that, in my understanding of the matter, the discovery 

 of this new part only adds to the perplexities of the subject, and deepens 

 the gloom that already surrounds PacJiytJieca. It is, however, my duty to 

 make this new evidence known, and I do it in this place, not out of 

 a conviction that PacJiytJieca is an Alga, but because, if it be a plant at all, 

 it is most probably an Alga, and in any case there is no evidence to 

 justify us in placing it elsewhere. 



Mr. John Storrie of Cardiff, who has done so much to further the study 

 of PacJiytJieca, sent to Mr. Carruthers the cup-like structure, with a PacJiy- 

 tJieca in it, which forms the new part about to be described. He says, in the 

 letter with which it was forwarded, that the specimen was quite loose in its 

 cavity, and that it ' was held in the cup like an acorn ; or a growth of some 

 arillus-like structure took place round it externally.' Mr. Storrie cut two 

 sections of the sphere, and he describes them in his letter as follows : ' The 

 section across the ends of the outer tubes I made from a piece that I thought 

 looked slightly different from the remainder of the outer skin, and, as I 

 think, had been connected with the cup at one time. Part of it still 



I L 



