Serpentinite of the Lizard, 291 



observed, so that their interior is amorphous and translucent. 

 Again, "where the prismatic structure is well defined, the 

 prisms, especially if they are large, have their interior in the 

 same condition *. These differences are clearly assignable to 

 different degrees of fibrous and prismatic development. 



Why some fasciculi are unlimitedly divided by which they 

 are made eminently fibrous — why some are formed of well-defined 

 prisms, and others, instead of being fibrous or prismatic, are en- 

 tirely amorphous — we shall make no attempt to explain; but it 

 may be remarked, with some confidence, that the ovoids resem- 

 bling Stenopora are each a fasciculus of prisms with their interior 

 in the amorphous condition. The remarkable appearance of 

 empty tubules in the ovoids that are finely prismatic we assume 

 to be caused by the interior of the prisms being imperfectly 

 Humiliated: opaque walls would necessarily intercept the light 

 in its passage into the interior of such small prisms. 



With respect to the spheres, we would suggest that they are 

 each the nucleus, in amorphous serpentine, of a mass of radia- 

 ting prismatic tremolite ; that the prisms radiated from and 

 originated on the surface of the nuclei, and were characterized 

 by opaque walls and a translucent interior ; that on the sur- 

 face of a nucleus, at their point of attachment, the internal trans- 

 lucency of the prisms produced the perforated appearances, and 

 their opaque walls the partitions which define the apparent 

 perforations. 



We cannot conclude without remarking that, organic-like 

 as the foregoing cases in tremolite appear to be in our speci- 

 mens, they are even more so than the figures we have given 

 convey an idea of ; indeed, although our best has been done 

 to give a faithful representation of them, our efforts have fallen 

 far short of depicting with sufficient exactness their wonderful 

 resemblance to the organisms which they simulate. 



EXPLANATION OF PLATE II, 



*** It will be understood that the figures represent things exhibited in 

 a number of specimens. Although this is the case, they are always repre- 

 sented in their own matrix ; whether it be serpentine, saponite, calcite, 

 or tremolite. The calcite having been slightly dissolved out, has its sur- 

 face below that of the other minerals. The four colours — green, fawn, 

 pale blue, and reddish — respectively represent serpentine, saponite, calcite, 

 arid tremolite. Where any of these minerals are in the granular or fioc- 

 culent condition, as often is the case, they are white ; and consequently such 

 cases are represented in this colour. 



Fig. 1. A pseudomorph, imbedded in serpentine, after a crystal of py- 



* Hexagonal prisms of calcite occasionally have a translucent interior 

 and an opaque exterior, but not due, as in tremolite, to structural variations. 



X2 



