DIFFICULTIES AND OBJECTIONS 239 



pearance. On either side of the serpentine band is 

 the nummuHne or proper wall, showing under a low 

 power a milky appearance, which, with a higher 

 power, becomes resolved into a tissue of the most 

 beautiful parallel threads, representing the filling of 

 its tubuli. Nothing can be more distinct than the 

 appearances presented by this wall and a chryso- 

 tile vein, under every variety of magnifying power 

 and illumination ; and all who have had an oppor- 

 tunity of examining my specimens have expressed 

 astonishment that appearances so dissimilar should 

 have been confounded with each other. On the 

 lower side tw^o indentations are seen in the proper 

 wall (c). These are connected with the openings 

 into small subordinate chamberlets, one of which is 

 in part included in the thickness of the slice. At 

 the upper and lower parts of the figure are seen 

 portions of the intermediate skeleton traversed by 

 canals, which in the lower part are very large, 

 though from the analogy of other specimens it is 

 probable that they have in their interstices, and at 

 their branching extremities, minute canaliculi not 

 visible in this slice. Fig. 2, from the same specimen, 

 shows the termination of one of the canals against 

 the proper wall, its end expanding into a wide disc 



