188 PEOCEEDIS-GS OF THE GEOLOGICAL SOCIETY. [Jan. 10, 



base, and of various- shaped granules, separated, or irregularly united 

 and clustered together — the latter being imbedded in the former. 

 The base consists of whitish-coloured calcite, or dolomite ; while the 

 granules, which "vary in size from the tenth to the fourth of an 

 inch," are of serpentine, or the allied minerals loganite and pyro- 

 sclerite, conspicuous by their green colour of various shades : in some 

 cases the granules consist of a white crystalline anhydrous mineral 

 (non-essential in Ophite) — a variety of pyroxene called diopside. 

 Often the granules are irregularly scattered through the base ; and 

 occasionally a number of them are united so as to form uneven- 

 surfaced plates, which affect a more or less parallel arrangement. 

 Ophite thus presents a spotted or laminated appearance. Besides, 

 its essential mineral, serpentine, is frequently aggregated into thick 

 complexly undulating layers, variously intermixed or intercalated 

 with aggregations of other silicated minerals, chiefly anhydrous, dif- 

 fering in colour ; and the calcite becomes expanded into layers of 

 saccharoidal marble : under these conditions Ophite assumes features 

 much more markedly stratified. 



Examined with a high power, the granules are seen to be generally 

 segmented or lobulated. Often the segmentations are very slight ; 

 and as often they are well pronounced, being here deep narrow 

 chinks, and there long subcylindiical necks, straight, or tortuous. 



The structure and composition of the granules, and their presence 

 in a calcareous matrix, were first made out in Ophite from Canada, 

 — most satisfactorily in that occurring at Grenville : this variety may 

 therefore be regarded as typically "eozoonal," particularly as the 

 above characters, and some others less obviously associated with them, 

 have been considered specially determinative of its " foraminiferal 

 origin." This being the case, we propose to include under the name 

 " eozoonal " all rocks which do not materially differ in their internal 

 structure from the one just described. 



"We have consequently placed in the " eozoonal " section the 

 varieties of Ophite which occur in Connemara, Donegal, and the 

 Isle of Skye, as well as others from India, Bavaria, and the State of 

 Delaware, specimens of all having passed under our examination*. 

 Ophitic rocks are also found in Anglesea, Saxony, Norway, the 

 Tyrol, Cornwall t, and Switzerland ; but in none of them have we 

 detected "eozoonal" characters, — a circumstance which, taken in 

 conjunction with some considerations hereafter noticed, disposes us 

 to suspect that they belong to a different section. 



III. General Characters of " Eozoon Canadense," 



According to the view which ascribes the form9,tion of "eojzoonal" 

 Ophite to the growth and reproduction of a forami^ifer, the sac- 



* We have not had an opportunity of examining any specime,ias of Ophite 

 from the Vosges ; but from Delesse's description of this rock (Ann. des Mines, 

 4^ ser. tome xviii. pp. 309-356), we a^e led ,to suspect that some of it Trill turn 

 out to be *' eozoonal." 



t From a fact stated hereafter there is some probability that Cornish Ophite 

 is "eozoonal." 



