550 



Description of the Figures in Plates XLI., XLIL, XLIIL, 

 and XLIY. 



Fig. 1. — Portion of a " chamber cast" from a transparent section of "eozoonal" 

 ophite from Canada : to show the changes which serpentine undergoes. At first 

 it is affected with fine linear separated divisions (a) ; which, through becoming more 

 numerous, give rise to chrysotile (b) : next is developed acicular chrysotile (c) ; 

 which passes into " true nummuline" layer, i.e. with the fibres or aciculi separated. 

 This section was presented to Dr. Rowney by Dr. Carpenter : as stated elsewhere, 

 we decalcified it. Figures 2, 3, 4, 5, and 7 are from the same section. The parts 

 are represented as seen by reflected light, and with a power magnifying 120 dia- 

 meters. 



Fig. 2 "Chamber casts" separated by interpolated calcite (calcareous or " interme- 

 diate skeleton"); this being dissolved out, the cavity, A, has taken its place. The 

 left " chamber cast," also the right one at the upper part, show fine linear sepa- 

 rated divisions (a), which, when numerous, produce chrysotile (c). (By mistake 

 this part is represented as consisting of what appear to be separated fibres ; but 

 they are in immediate contact). At d, d, the fibres represent " true nummuline 

 layer." It will be observed that the fibres exactly correspond in direction with 

 the linear divisions in the serpentine ; which clearly proves that both kinds have 

 one and the same origin. 210 diameters : opaque. 



Fig. 3 Lump of serpentine, breaking up into "chamber casts." The intervening spaces 



are filled with plates and " amorphous masses" (Carpenter) of granular flocculite ; 

 in some places this substance is rudely fibrous. At A (cavity) the flocculite is re- 

 placed by calcite (dissolved out), and the rude fibres by " true nummuline layer." 

 210 diameters : opaque. 



Fig. 4. — Enlarged representation of a portion of Dr. Carpenter's section, showing the 

 layers of "chamber casts" (a), and "intermediate skeleton" (b), obliquely divided 

 by parallel cracks or fissures (c). Opaque. 



Fig, 5. — Representation of one of the cracks (C), marked c x in fig. 4, lined with chry- 

 sotile (c), which is often in the state of " true nummuline layer" (d). Opaque. 

 The fibres, it must be understood, are in close contact, though apparently not so in 

 the figure. 



Fig. 6. — Vein or crack (intersecting serpentine in a slab of Connemara ophite), filled 

 with chrysotile in its various modifications. The upper portion of the vein passes 

 through " chamber casts;" and here it consists of both juxtaposed (c) and sepa- 

 rated (a) aciculi : the last variety, which is undistinguishable from " true num- 

 muline layer," is also seen on the adjacent segmented granules, marked d. On 

 entering the vacancy A, the vein, here typical chrysotile, becomes divided into 

 two portions ; the division, d, being separately acicular ; and the other, c, asbes- 

 tiform. 



Fig. 7. — Decalcified portion of " intermediate skeleton," containing plates, rods — branch- 

 ing and simple — characteristic of the "canal system;" also "amorphous masses" 

 (A, B) or flocculent modifications of the latter. At B x, the serpentine is seen 

 changing into the above. (This figure fails to give a proper idea of the changes 

 exhibited by the serpentine). Opaque. 



Fig. 8 Portion of serpentine in a specimen of decalcified ophite from " Neybiggen," 



divided by lamellar (a) and fibro-lamellar (£) cleavages. These two divisional 

 structures break the serpentine into prisms ; which, losing their edges, become 

 vermicular and separated (c), at the same time changing from green to white. 

 In the latter state the configurations closely resemble the simple " definite shapes" 

 of the " canal system." Opaque : 120 diameters. Figure 8, %, represents a trans- 

 verse section of a prism, formed by the two sets of cleavage (imperfectly delineated, 

 however). 



Fig. 9- — Portion of a decalcified vein or crack intersecting serpentine in a slab of 

 Connemara ophite. Both sides are lined with various modifications of chrysotile, — 

 asbestiform at c, and separately acicular at d. The bottom of the vein (darker 

 coloured) is filled with fibrous calcite: the same substance occupied the spaces 

 between the two fringes of chrysotile, also the openings between the separated 

 aciculi, before decalcification. Opaque : 60 diameters. 



