VIl] 



SOLENOPORA. 



189 



affords a good illustration of the manner of occurrence of fossil 

 coralline algae in association with corals and other organisms'. 



In the fossil species of Lithothamnion hitherto recorded there 

 do not appear to be any important features in which they differ 

 from recent forms ; the geological history of the genus so far as 

 it is known, favours the view that the generic characters are of 

 considerable antiquity. 



Solenopora. Fig. 38. 



Mr A. Brown^, of Aberdeen, has recently brought forward 

 good evidence for including various calcareous fossils, described 

 by several authors under different names and referred to various 

 genera of fossil animals, in the genus Solenopora, which he 

 places among the coralline algae. 



Species of this genus have been described from England, 

 Scotland, Esthonia, Russia, and other countries. The geological 

 range of Solenopora appears to be from Ordovician to Jurassic 

 rocks ; in some cases it is an important constituent of beds of 

 limestone. 



Solenopora compacta (Billings). Fig. 38. This species 

 was originally described by Billings as Stromatopora compacta, 



Fig. 38. 



Solenopora compacta (Billings). A. Tangential section, x 100. 

 B. Vertical section, x 50. (After Brown.) 



1 Vide Walther (88) p. 499 ; also Jukes-Browne and Harrison (91) passim. 

 I am indebted to Mr G. F. Franks, who has studied the Barbadian reefs, for 

 the opportunity of examining sections of West-Indian coral-rock. 



2 Brown A. (94). 



