Vir.] PALAEOZOIC SIPHONEAE. 171 



those by Munier-Chalmas^, Cramer'', Solms-Laubach', and 

 Church", may be mentioned. 



The publication of a short preliminary note by Prof. Munier- 

 Chalmas in the Gomptes Rendus for 1877 was the means of 

 calling attention to the exceptional importance of the calcareous 

 Siphoneae as algae possessing an interesting past history, of 

 which satisfactory records had been preserved in rocks of various 

 ages. Decaisne had pointed out in 1842 that certain marine 

 organisms previously regarded as animals should be transferred 

 to the plant kingdom. Such seaweeds as Halimeda, Udotea, 

 Penicillus and others were thus assigned to their correct 

 position. Many fossil algae belonging to this group continued 

 to be dealt with as Foraminifera until Munier-Chalmas demon- 

 strated their true affinities. In Gumbel's monograph on the 

 so-called NuUipores found in limestone rocks, published in 1871°, 

 several examples of siphoneous algae are included among the 

 fossil Protozoa. 



In recent years there have been several additions to an 

 already long list of fossil Siphoneae. In addition to the 

 numerous and well-preserved specimens, representing a large 

 number of generic and specific forms, which have been collected 

 from the Eocene of the Paris basin, there is plenty of evidence 

 of the abundance of the members of the Dasycladaceae in the 

 Triassic seas. In the Triassic limestones of the Tyrol, as well 

 as in other regions, the calcareous bodies of siphoneous algae 

 have played no inconsiderable part as agents of rock-building* 

 Genera have been recorded from Silurian and other Palaeo- 

 zoic horizons, and there is no doubt that the Verticillate 

 Siphoneae of to-day are the remnants of an extremely ancient 

 family, which in former periods was represented by a much more 

 widely distributed and more varied assemblage of species. 

 There is probably no more promising field of work in the 

 domain of fossil algae than the further investigation of the 

 numerous forms included in Munier-Chalmas' class of Siphoneae 



1 Munier-Chalmas (77). ^ Cramer (87) (90). 



3 Solma-Laubach (91) (93) (953). i Church (95). 



6 Gumbel (71). " Beneoke (76). 



