206 PEOCEEDINGS OP THE GEOLOGICAI SOCIETY. [Jan. 10, 



lost their original forms {cylindrical, flattened, or branching) through 

 superinduced crystallization. If such an hypothesis ibe admitted, 

 the imbedded crystalline aggregations, with which many of the Con- 

 nemara, Donegal, and other saccharoidal marbles are loaded, may be 

 considered, with equal reason, to be the metamorphosed or crystallized 

 representatives of the " canal-system of Bozoon." Another consider- 

 ation may be adduced: Ophite, consisting of dark-green serpentine, 

 or more probably loganite, is of common occurrence at Lisoughter, 

 intermixed with, and passing into white or yellowish crystalline tufts, 

 averaging an inch in length. We find the latter to be structurally 

 and, to aU appearance, chemically identical with the micro -crystal- 

 line aggregations which occur in the true " eozoonal " variety from 

 the same place. 



JSTow we would ask any mineralogist to make himself acquainted 

 with the known modifications of the " canal-system" of foraminifers*, 

 and to conceive the possibility of such modifications assuming cha- 

 racters identical in every respect with ordinary scopiform crystal- 

 lization — precisely such as are met with among zeolites, kermesite, 

 and a number of other minerals f. Let him compare the latter with 

 the presumed metamorphosed representative of the ^' canal-system," 

 given in figure 14, PL XV., magnified 210 diameters, of which the 

 original occurs in a decalcified specimen of " eozoonal" Ophite from 

 Lisoughter ; and let him consider that this is a fair example of what 

 he is required to believe was once '' an internal cast of an arbores- 

 cent ' cluster ' of passages originally occupied with sarcodic prolonga- 

 tions." 



The dissimilarities existing between the "definite shapes" and 

 the crystalline aggregations are simply such as obtain among a 

 number of minerals J. Aragonite differentiates itself in a similar 

 manner, being crystallized or coralloidal according to circumstances§. 

 Native silver is perhaps more in point, as beautiful dendritic forms, 

 some composed of microscopic crystals, others of the metal in the 

 amorphous state, frequently occur imbedded in calcite. 



Eut admitting in the widest sense the dissimilarities which have 

 been noticed, they nevertheless do not, in our opinion, weaken in the 



* Numerous examples are given in Carpenter's ' Introduction to the Study 

 of the Foraminifera.' 



t Fossil corals, echinoderms, and shells may have their skeletons replaced 

 by dolomite, calcite, selenite, and other mineral substances ; but we confess to 

 be unacquainted with a single instance in which a portion of this part has be- 

 come transformed into crystals passing beyond its surface. As a case in point, 

 the corals occurring in the dioritic rock of Rothau, in the Vosges, are changed 

 into hornblende, garnet, and axinite, without any alteration of form. (See 

 ' Annales des Mines,' 6^ serie, vol. xii. p. 318.) 



J To show one of the principal differences referred to, we may instance the 

 example under fig. 3 in the "tinted plate" appended to Dr. Carpenter's paper 

 in the ' Intellectual Observer, and the one represented in our figure 14, pi. XV. 



§ Beudant has given, in his ' Mineralogie,' p. 49, a representation of a coral- 

 loidal form of Aragonite, which strikingly resembles the " representative of the 

 canal-system," given by Dr. Carpenter in the plate cited in the last note. Of 

 course the former may have been developed in a fluid medium, — a condition, 

 however, to which we do not attach much importance. 



