256 EESOEIMITE CATALOGUE 



Note. — Several more or Jess doubtful species which could 

 technically he placed in the genua Algites have been described 

 from time to time. Their bibliographic details, however, are 

 not worth bringing together. Many of the "species" will be 

 fonnd in the list of Cretaceous species given at the beginning of 

 this volume. 



Order RHODOPHYCE^— CORALLTNACE^. 



Algse, principally marine, with branched and sometimes very 

 complex thallus. Multicellular, with some cell-differentiation 

 and a more highly organised reproductive system than in the 

 other groups of Algse. The calcareous encrusting of the thallus 

 and the form of growth give a number of the species the 

 appearance of corals. The chromatophores (as in all Ehodo- 

 phj'cese) contain a red colouring-matter. 



Genus LITHOTHAMNIUM, Philippi. 



[Living genus. J 



A coralline Alga with an encrusting, spreading thallus growing 

 on to the sub-stratum, with irregular, coralline, or branching 

 upward outgrowths. Thallus entirely calcified and as hard as 

 stone. Basal part of thallus with a regular arrangement of the 

 cells in rows. Conoeptaoles developed in the upward growing 

 part of the thallus, generally in series of growth-zones. 



As the living genus was long unrecognised as belonging to 

 the Algae, it is not surprising that fossil representatives of the 

 group remained even longer without detection. It was in 1874 

 that the first S5'stematic description of the fossil forms of 

 .Liihoihamnium appeared bj Giimbel under the title " Die 

 sogenannten NuUiporen." In this worlc seven Cretaceous 

 species are described in addition to those of Tertiary and 

 Jurassic age. Ilothpletz (1891 b), under the title " Possile 

 Kalkalgen aus den Familien der Codiaceen und der Corallineen," 

 has added the only other important contribution to the subject, 

 in which he describes four new Cretaceous species of Litho- 

 thamnium. Solms-Laubach in his ' Text Book of I'ossil Botany ' 

 says that " we shall do well .... to put them all together as 



