782 EEPOKT— 1893. 



carbonaceous material in a more or less fragmentary condition, but sufficiently 

 continuous to enable the existence of three layers to be determined : an outer 

 and inner, which are very thin, separated by a space, now filled with calcite, from 

 a thicker middle layer, which measures from 0-005 to 001 mm. across. The 

 middle layer sometimes breaks up into threads, and the superficial films have a 

 reticular appearance, which may, however, be due to post-mortem changes. In 

 the region of the virgula and also along the free edges of the thec£e the wall 

 thickens, partly by an enlargement of the space between the layers, and partly by 

 a thickening of the middle layer. Thus, in one example the torn thickness of the 

 wall in the virgular region is 0075 mm., and of the virgula itself, which represents 

 the middle layer, 0'037 mm. ; similarly at the margin of the theca the total thick- 

 ness was found to be 0'085 mm., the included middle layer measuring 0'045 mm. 

 Thin threads of carbonaceous material extend from the middle to the superficial 

 layers, and are particularly obvious in the thickened regions. The virgula would 

 appear to possess no independent existence ; it seems to be merely a thickening of 

 the middle layer. 



5. Report on the Circulation of Underground Water. 

 See Reports, p. 463. 



[Maps, specimens, and photographs of geological interest were exhibited each 

 day in the Temporary Museum from 10 a.m. to 6 p.m.] 



