212 PEOCEEDINGS OP THE GEOIOGICAL SOCIETY. [Jan. 10, 



acting transversely to the planes of the one or of the other, thereby 

 metamorphosing the rock to the extent of thoroughly crystallizing 

 it, and even in many cases producing a lamination often honey- 

 combed perpendicular to its bedding. 



But what is of special importance, as bearing on the subject of the 

 present memoir, is the complete similarity existing between many of 

 the configurations, and the granules and plates of serpentine, in 

 shape, mutual attachment, and arrangement. 



Building Hill, near Sunderland, aifords (at least this was the case 

 some years ago, before it was converted into the People's Park) in- 

 numerable specimens of the globular and botryoidal kinds, which, 

 when cleared of the earthy matrix, are perfect imitations, on a 

 gigantic scale, of the ^'chamber- casts," in their form and ^'acervuhne" 

 arrangement*. We have given a representation in fig. 18, PI. XY., 

 of a specimen freed of its matrix, collected many years ago, with- 

 out, of course, any reference to the question at issue. Its general 

 resemblance to decalcified specimens of Ophite, where there is an 

 association of " acervuline " and laminar " growths," cannot but be 

 admitted to be most striking. 



But not only do the configurations simulate the forms and ar- 

 rangement of the granules and plates of serpentine ; they equally 

 simulate and illustrate the '' definite shapes." Specimens may be 

 procured presenting dendritic ramifications, or a sheaf -like divergence, 

 or appearing like solid bunches of rounded forms, composed of car- 

 bonate of lime, and imbedded in or penetrating the calcareo-mag- 

 nesian matrix, just as the hydro-silicated magnesian "definite shapes," 

 and imitations of a '^ sailor's swab," occur in the calcareous septa of 

 " eozoonal " rocks. Reduced to microscopic dimensions, many of 

 them w^ould resemble certain of the structures represented by Daw- 

 son t, Carpenter J, and Jones §. 



YIII. " Intermediate Skeleton^' 



Already sufficient has been stated to show that this part is com- 

 pletely paralleled by the matrix of certain minerals. The saccha- 

 roidal calcareous gangues of chondrodite and pargasite closely cor- 

 respond to the " skeleton," as it exists in " eozoonal" Ophite from the 

 State of Delaware, and in specimens we have collected at Barna 

 Oran and Lisoughter : in the rocks alluded to the septa exceed in 

 width the diameter of the granules !|. The matrix of bowenite from 

 Rhode Island, and that of metaxite from Eeichenstein, also the sac- 

 charoidal calcite of the coccolite marble of Tyree, may be adduced 

 as other instances in point. 



The part under notice passes into the layers and beds of saccha- 



* An association of the kind is shown in the coloured plate accompanying 

 Dr. Carpenter's paper in the ' Intellectual Observer.' 



f Quart. Journ. Geol. Soc. vol. xxi. pi. vii. fig. 3 (a, a). 



X Ibid. vol. xxi. pi. viii. fig. 6 b, and pi. ix. figs. 5 a, b,c,d; also ' Intellectual 

 Observer,' vol. vii. " uncoloured plate," fig. 3. 



§ Popular Science Review, vol. iv. pi. xv. figs. 5, 6, 7, and 8. 



II Is not this the case occasionally in Burgess Ophite ? its septa being " in 

 some parts more than 30 millimetres in thickness " (Hunt, Quart. Journ. Greol. 

 Soc. vol. X xi. p. 69). 



