346 Prof. H. A. Nicholson — On the ' Guelph' Limestones. 



Dolomites both in Canada and Ohio. Most usually the actual fossil 

 itself has disappeared, and there is nothing left but the little cavity 

 where it was situated ; but in other cases the substance of the fossil 

 has been preserved. Pending a microscopic examination of these 

 problematical little bodies, nothing can be said of them beyond that 

 they are very probably of the nature of calcareous sponges, and 

 possibly belong to Astylospongia. 



The corals of the Guelph Formation are neither very abundant nor 

 very widely distributed. In Canada, the most characteristic corals 

 are Favosites polymorpha, Goldf., Favosites {Astro cerium) venusta, 

 Hall, and F. Jiernispherica, Yandell and Shumard, along with a 

 species of Amplexus (apparently A. Yandelli, Edw. and Haime), and 

 a fasciculate form which seems to be intermediate in its characters 

 between Amplexus and Diphyphyllum. At Cedar ville, in Ohio, I 

 detected Favosites Gotldandica, Lam., an undetermined species of 

 Syringopora, a large Chonophyllum allied to C. perfoliatum, Goldf., 

 and numerous specimens of an ill-preserved species of Cladopora, 

 resembling C. reticulata, Hall. Halysites catenularia, Linn., is also 

 not of uncommon occurrence, and there are other forms which have 

 not been satisfactorily determined. 



The remains of Crinoidea are rare or unknown in the Guelph 

 Formation of Canada ; but very numerous and singular forms 

 belonging to this group and to the nearly allied group of the 

 Cystoidea have been found in the corresponding deposits in Ohio, 

 Wisconsin, Illinois, and Iowa. Amongst the Crinoids, the more 

 important forms belong to the genera Eucalyptocrinus, Cyathocrinus, 

 Actinocrinus, Melocrinus, Ichthyocrinus, Rhodocrinus, and Glyptaster. 

 Amongst the Cystideans, we have not only such well-known species 

 as Caryocrinus ornatus, Hall, but we find forms belonging to the 

 remarkable genera Gomphocystites, Solocystites, Fchinocystites, and 

 Crinocystites, together with species of Apiocystites and Hemicosmites. 



The Polyzoa of the Guelph Formation have not as yet been 

 worked out, so far as I am aware. In Canada, I have never 

 succeeded in detecting any examples of this class in the Guelph 

 dolomites ; I found them, however, to be very abundant, though 

 badly preserved, at Cedarville and Clifton in Ohio. The most 

 abundant are Fenestellce, belonging to at least three species. Very 

 abundant, also, is a species apparently referable to Hall's genus 

 Lichenalia (= Cyclopora, Prout?). A very similar form is found in 

 the underlying Clinton Formation at Yellowsprings, a few miles to 

 the north of Cedarville, and it constitutes one of the commonest and 

 most characteristic fossils of the formation. The species is clearly 

 distinct from Lichenalia concentrica, Hall, which occurs in the 

 Niagara group proper, and seems more closely to resemble ihe 

 Cyclopora polymorpha, Prout, of the Sub-Carboniferous series ; but 

 further examination will probably show it to be new. Lastly, there 

 occurs a species of Ptilodictya, also apparently new. 



The Brachiopoda of the Guelph Formation are individually very 

 numerous, and are highly characteristic. Foremost amongst them 

 come the Trimerellids, which the researches of Billings, Dall, Lind- 



