178 THALLOPHYTA. [CH. 



Masne, as being in places full of the delicate remains of algae 

 having the form of branched filaments, and appearing in sections 

 of the rock as white lines on a dark crystalline matrix. In 

 fig. 35, G, one of these Sardinian specimens is represented. This 

 form is named Confervites Chantransioides^ ; the thallus consists 

 of branched cell-filaments, having a breadth of 6 — 7/x, and 

 composed of ovate cells. It is possible that this is a fragment 

 of a Cambrian alga, but the figures and descriptions do not 

 afford by any means convincing evidence. From post-Tertiary 

 beds various genera, such as Vaucheria and others, have been 

 recorded, but they possess but little botanical value. 



INCERTAE SEDIS. 



Fossils in Boghead ' Coal ' referred hy some authors to 

 the Chlorophyceae. 



During the last few years much has been written by two 

 French authors, Dr Renault and Prof Eertrand, on the subject 

 of the so-called Boghead of France, Scotland, and other 

 countries. They hold the view that the formation of the 

 extensive beds of this carbonaceous material was due to the 

 accumulation and preservation of enormous numbers of minute 

 algae which lived in Permo-Carboniferous lakes. 



In an article contributed to Science- Progress in 1895 I 

 ventured to express doubts as to the correctness of the con- 

 clusions of MM. Renault and Bertrand'^ Since then Prof 

 Bertrand has very kindly demonstrated to me many of his 

 microscopic preparations of various Bogheads, and I am in- 

 debted to Prof Bayley Balfour of Edinburgh for an opportunity 

 of examining a series of sections of the Scotch Boghead. The 

 examination of these specimens has convinced me of the 

 difficulties of the problems which many investigators have tried 

 to solve, but it has by no means led me to entirely adopt the 

 views expressed by MM. Bertrand and Renault. 



The Boghead or Torbanite of Scotland was rendered famous 

 by a protracted lawsuit tried in Edinburgh from July 29th to 



1 Bornemann (91) p. 485. Pis. 42 and 43. 2 Seward (952) p^ 3^7^ 



