Notices of Memoirs — A. W. R. Don on Parka decipiens. 469 



To sum up, then, the flora represented in the Pettycur Limestone 

 appears, on the whole, to contain more generalized and simpler types 

 than occur in the Coal-measure and later strata, and these types may 

 be arranged in order so as to suggest certain possible lines of 

 evolution, 



VII. — On the Nature of Parka decipiens.^ By Archibald W. E. 



Don, B.A. 

 n~lHIS paper was the outcome of an attempted re-investigation of 

 JL Parha, chiefly microscopical, with the aid of Schultz's solution 

 (strong nitric acid and potassium chlorate). Being the only common, 

 and quite the most characteristic fossil of the Lower Old Hed Sand- 

 stone of ,the Kincardine-Forfar-Perth area, it has naturally attracted 

 considerable attention. The nature of Parha has been a subject of 

 speculation ever since its discovery at Parkhill in 1831 by Dr. Fleming. 

 He described it as probably allied to Juncus or Sparganium,, and 

 Hugh Miller, on the whole, agreed as to its vegetable nature. Mantell 

 stoutly maintained it to be ' batrachian eggs '. Lyell thought it the 

 egg-packet of Pterygotus, and this determination was accepted by 

 Salter, Woodward, Powrie, and others. In 1890, however, Messrs. Reid, 

 Graham, and Macnair, having convinced themselves of its vegetable 

 nature, sent specimens to Sir W. Dawson, who, with Professor Penhallow, 

 submitted it to a microscopical examination. They clearly showed it 

 to be vegetable, and after boUing it in nitric acid, demonstrated the 

 presence of spores within the carbonized tissue. 



The conclusions, other than this main one, arrived at by former 

 investigators have not as yet been confirmed by the present re-examina- 

 tion, the chief results of which, therefore, tend unfortunately to be 

 more destructive than constructive. Hitherto no evidence for heterospory 

 has appeared. The ' prothalli ' have not been found. The mode of 

 attachment and other vegetative features have not been elucidated, 

 and an agnostic attitude is assumed, pending further discoveries, with 

 regard^ to those formerly attributed to Parka. No evidence has appearetj 

 with regard to the supposed varieties ' media ' and ' minor \ An 

 attempt, admittedly tentative, has been made to form some conception 

 of the original structure and shape of Parha, based on examination of 

 certain excellently preserved impressions of its two surfaces. The main 

 conclusion is that the original spore-containing tissue was almost flat, 

 not spherical (and made up of numerous adjacent lens-shaped spore-sacs) 

 — a structure, in fact, in no way comparable to anything Hydropteridian, 

 and unlike any known sporangia of to-day. There was, certainly, 

 intimately connected with it a so-called ' indugium '. Such a re- 

 construction must, however, be understood to be hypothetical, and not 

 an ascertained fact. Certain cell-Jayers and tissues revealed by the 

 more gentle action of the Schultz's solution may, however, help towards 

 an ultimate solution of the perennial problem of Parha decipiens. 



VIII. — Discovery of Fossils in the Boundary Fault Series, near 

 Aberfoyle.i By T. J. Jehu, M.A., M.D. 



THIS Series is well exposed between Loch Lomond and Callander, 

 forming a narrow belt separated by a reversed fault from the 

 Lower Old Red Sandstone on the south-east, and probably by a line of 

 thrust from the Leny Grits on the north-west. It consists of black 

 and grey shales, cherts, grits, and calcareous beds, with which are 

 associated some altered igneous rocks. Adjoining the crushed and veined 

 rock which runs along the boundary of the Lower Old Red Sandstone, 

 patches of sheared serpentine are seen at several places, sometimes 



•* Abstract of paper read before the British Association, Section C (Geology), 

 Dundee, September, 1912. 



