72 A New Part of Pachytkeca. 



remains in the original state Please notice the shiny black external 



coating still remaining on one part of the Pachytheca* (plate XVIII., fig. i). 

 Mr. Storrie thought that this shiny outer layer would repay cutting 

 through. I may say at once that the sections cut for me of the remainder 

 of the Packytheca-sphere have revealed nothing new whatever, not even 

 the section which passed through the outer coat just mentioned (plate 

 XVIIL, fig. 3). The sections (plate XVIII., figs. 2 and 3) have been useful 

 only in determining beyond question the fact that it is a true Pacliythcca 

 which rested within the cup. 



The cup surrounded one half of the sphere ' like an acorn,' as Mr. Storrie 

 says, or as an egg-cup holds an egg. On the outside, the cup is clothed 

 with hairs (plate XVII., figs. I, 3 and 4) on the lower portion, and is other- 

 wise smooth. The broken edge (plate XVII., fig. 2) shows that the cup 

 itself is chambered radially and these chambers appear to spring from 

 an axial body the top of which may be seen in the bottom of the 

 cup (plate XVII., figs. 2 and 3). My first idea was that this projecting 

 axis would be found to correspond with the dimple found in many 

 specimens of PacJiytlieca, but this portion was not among the parts sent by 

 Mr. Storrie ; probably it was the part he used in making his two sections. 

 However likely such a view may be, I have no evidence of it. Unfortu- 

 nately the structure of the interior of the cup, as seen in vertical section, has 

 not been preserved, and a microscopical examination of it reveals only purely 

 mineral structure. We know, however, from examining its broken edge, 

 that the cup was radially chambered, like the sporangial rays of Acetabu- 

 laria, and in fact the cup itself (without the Pac/tyt/ieca-sphere) is not unlike 

 the remains of some organism like Acetabularia, and the resemblance is 

 heightened by the axial body in the centre. Suggestions of this kind are, 

 however, plainly of no use, since in none of the verticillate SipJioncce is 

 there anything to correspond with the sphere of Pachytkeca. There is, in 

 fact, no alga, nor any other plant known to me, which lends itself for 

 comparison with Pacliytlieca. 



Since the Pachyt/icc a- sphere was loose in the cup, there must have been 

 a tissue, now perished, between the ends of the radiating filaments of the 

 sphere and the chambers of the cup. My only hope of gaining farther 

 light is in the discovery of specimens in which this tissue has been preserved, 

 and more of the cup and axial portion or that perhaps, in the mean 

 time, some zoologist may recognise it, and relieve botanical literature 

 of this standing puzzle. 



I am much indebted to Mr. John Storrie, who found this unique 

 specimen and to Mr. Carruthers for the opportunity he kindly gave me of 

 making it known. GEORGE MURRAY. 



