110 



G. E. TINE ON PHTLLOPOEA AND THAMNISCrS PEOM THE 



thick. In places where the whole of the cells are worn off, their 

 former localization is indicated by wavy outHnes, as shown in 

 fig. 1, E ; but I cannot trace any other special character of the reverse 

 than this. "VYith the exception of the prominent lips of the cells of 

 the species, nearly the whole of the original organic matter of both 

 specimens is replaced by iron oxide ; consequently the once living 

 form now appears upon the shale as a dark brown friable mass. 

 Because of this, I am unable to fill in all the details that are necessary 

 for the full study of Lower Silurian species. It is to be hoped, 

 however, that the publication of these brief notes may be the means 

 of bringing to the front other fossils with the poriferous face 

 exposed, rare though they may be. 



Prof. H. A. Nicholson has described one species of PJiyllopora 

 from the Trenton Limestone, Peterborough, Ontario *, and as the 

 Trenton Limestone is of, or about, the same age as our Caradoc 

 beds, the species is interesting for the sake of comparison. The 

 Ontario form is named Retepora trentonensis, Mch., and the fossil 

 was only known to the author " by several more or less imperfect 

 specimens, from which some of the essential characters cannot be 

 determined." There is no possibility of uniting the two forms under 

 one specific name, because, even from the characters which Prof. 

 ^Nicholson was able to draw up from the best of his specimens, there 

 are many differences between them, as a comparison of the two 

 descriptions will show. The Ontario specimens are better preserved 

 than ours, and we learn from the description that the '- reverse 

 aspect is strongly striated with wavy or straight longitudinal striae." 

 In the Caradoc species I cannot trace any other character of the 

 reverse aspect than that already given. 



Mr. E. 0. Ulrich describes t and figures one species of PTiyllojjora 

 in his series of papers on " American Palaeozoic Bryozoa." This he 

 names F. variolata, Ulr., but he says "the genus is represented by 

 two species in the Cincinnati rocks, P. variolata and another 

 which I believe is the same form that was described by Miller and 

 DyerJ under the name of Intricaria clathrata." The species found 

 in our British rocks is related to, but not identical with, Mr. Ulrich's. 

 In his species the " cell-apertures are arranged .either in two series 

 or three alternating rows; intercellular spaces thin, raised into 

 small nodes where longer ; about fourteen cell-apertures occupy the 

 space of -1 inch. Branches on non-celluliferous side smooth." 



Locality. Cincinnati, Ohio, in strata from 150 to 325 feet above 

 low-water mark, in the Ohio river. 



There is another fossil in Mr. Morgan's collection that merits 

 distinction and description, not more on account of its peculiarly 

 antique character than on account of its mode of preservation in 

 the volcanic ash in which it is imbedded. 



* New Palaeozoic Polyzoa, Geol. Mag. Dec. 2, vol. ii. p. 2, f. 4, 4 b. 

 t Journal Cincin. Soc. Nat. Hist. Oct. 1882, p. 160, pi. vi. f. 14. 

 \ Contributions to Palaeontology, no. 2, 1878. 



