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Cincinnati Society of Natural History. 



made to include some remarkable ovate forms which have been the ones 

 best known as species of the genus. These two species are Rusophycus 

 bilobatum and R. pudicum. In the former the general outline is elliptical, 

 with the surface sometimes nearly smooth, sometimes very rugose, and the 

 specimens varying in size from an inch long and half an inch wide, to four 

 inches long and three inches wide. A longitudinal groove runs the whole 

 length of the fossil, dividing it into two distinct lobes. Occasionally an 

 apparent stem is found attached to the central depressed groove, but gen- 

 erally this is absent. The distinguishing feature is the bilobate form. 



In the latter species (pudicum) the specimens are also elliptical, are gen- 

 erally much smaller, smooth, and with the groove deep in the center, but 

 disappearing before either end is reached. 



Two other species of the genus were described by Professor Hall, viz., 

 R. clavatum and R. subangulatum. These are quite different in appearance 

 from those already noticed. Instead ot being elliptical they are elongated, 

 very many times longer than wide, with a depressed line along the center and 

 obscure transverse ridges. In the Journal of this Society (Vol. I., p. 25) 

 Miller and Dyer described another species of the genus under the name of R. 

 asperum. This differs from all those of Hall, in being quite rough, with 

 " numerous papillae," and lacking the transverse rugae or wrinkles. In the 

 Palaeozoic Fossils of Canada (Vol. I.), Dr. Billings characterized a species 

 under the name of R. grenvi/msis. 



After Hall had described and figured his species, it was found that 

 D'Orbigny had, in 1842, described similar forms under the name of 

 Cruziana. According to the rules of nomenclature this name must be 

 used instead of Rusophycus, and to it all the species should be referred. 



Under this last generic name Billings has described one species from 

 Canada (Palaeozoic Fossils, Vol. II.), viz., C similis. This is similar to 

 bilobata and pudica, in having the longitudinal line and the transverse 

 rugae, but differs in being longer and not elliptical. Dr. Charles White, 

 in the Palaeontology of Wheeler's Survey West of the Hundredth Meridian, 

 describes and figures two other species of Cruziana, more like the ones of 

 Hall. These two are C Linnarsoni and C rustica, and are from the Pri- 

 mordial Sandstone of Arizona. Both are elliptical in shape, and the first ap- 

 proaches C. pudica, while the last is close to C bilobata, though the rugae 

 are more numerous and closer together. Neither of these show any traces 

 of a stem. 



Principal Dawson, of Montreal, in the Canadian Naturalist, proposed 

 for these forms the name of Bttsichnites, and in Acadian Geology, pp. 

 257 and 410, figured two species from the Carboniferous. One of them he 



