4 SIE WILLIAM DAWSON 



In the sixth edition of "The Elements" Lyell figures two specimens, one of them 

 lying in a mass of the Zostera-like leaves described by Fleming and Miller. He compares 

 them with the eggs of Natica, and also with dried-up eggs of frogs, as observed by Man- 

 tell, but inclines to the view that they may have been ova of some species of Plerygotus, 

 and states that they seem to have constituted " a single layer of ova enclosed in a sack." 

 Mr. Powrie is referred to as holding this opinion. In " The Students' Manual," 4th edi- 

 tion, revised by Duncan, the same views are stated. Lyell distinguishes from Parka cer- 

 tain larger round discs, found separately and in small clusters, without any envelope, and 

 in a letter from Mr. Powrie, kindly communicated to me, that gentleman refers to these 

 as different from Parka, and also from the globular smooth objects described as Pacliytlieca 

 by Hooker and referred to in my former note. Mr. Powrie has described the beds in For- 

 farshire holding these specimens, in two excellent papers in the ' Journal of the G-eological 

 Society of London,' ' and in the latter of these he states his views as to the probable nature 

 of Parka, more especially referring to the fact that numerous remains of Pterygolus and other 

 crustaceans occur in the beds. It is to be observed, however, that in some of the beds 

 vegetable remains are much more abundant than those of crustaceans. 



Murchison notices the Forfarshire beds holding Parka, in Silnria (239 and 250 et seq), 

 referring them to the base of the Devonian, agreeing in this with Mr. Powrie in the 

 papers above referred to. The characteristic fossiliferous beds are those known as the 

 Arbroath flagstones. As shown in "The G-eological Map of Scotland," the outcrop of 

 these Lower Devonian beds extends in an oblique band through Forfarshire and Perth- 

 shire, and it is from this belt that most of the specimens referred to in the following pages 

 were collected. 



Page, in his "Advanced Text-book,"- notices Parka, and endeavours to solve the 

 difficulty by figuring three specimens as respectively " vegetable," " moUuscan spawn," 

 and "crustacean spawn." The first figure represents a small specimen with remains of 

 an indusium. The second is a larger specimen destitute of any covering. The third is a 

 group of a few larger rounded bodies with central dot, and probably diflerent from Parka 

 decipienx, or at least from the ordinary type. He adds that he is inclined to regard many 

 of the very numerous specimens he has studied as vegetable, but others may have been 

 the spawn of mollusca or more probably of Crustacea. 



In G-eikie's "Text-book of Geology " these objects are referred to as " clusters of crus- 

 tacean egg-packets," A similar view is adopted by Woodward in his memoirs on 3Iero- 

 stomala in the publications of the Palteontographical Society. 



As stated above, the credit of directing renewed attention to these fossils belongs 

 primarily to Mr. Reid of Allan House, Blairgowrie, and to Mr. Graham of Rescobie,^ both 

 of whom have collected large suites of specimens, and both were strongly impressed with 

 their vegetable nature and with their possible affinities with rhizocarpean forms of vege- 

 tation similar to those which I had described in " The Geological History of Plants," from 

 Ohio and from Brazil. To Mr. Reid I am indebted for placing at my disposal his large 

 collections, and for many valuable notes as to localities, mode of occurrence and probable 

 nature of the fossils, and to Mr. Graham for similar notes and for specimens sent through 

 Mr. Reid. 



1 Vol. xvii, pp. 534 et seq. : vol. xx, pp. 413 et seq. 



■' 1856, page 127. 



" Mr. Reid in hia letters also refers to Mr. MacNair as having assisted in working out stratigraphical details. 



