PALEOZOIC TIME LOWER SILURIAN. 



501 



rock of Philipsburg, Canada East; Piloceras Canadense B., from the Mingan Islands, 

 north of Anticosti Island; P. Wortheni B., from western Newfoundland. Nautilus 

 pomponius B. is from Philipsburg ; N. ferox B. , Mingan Islands, is referred by Hyatt to 

 the genera Plectoceras and Litoceras, there being no true species of Nautilus in Paleozoic 

 rocks. At Philipsburg, Fort Cassin, and in Newfoundland, the fauna included also, accord- 

 ing to Hyatt, species of the genera Sannionites (Fischer, Hyatt), Endoceras Hall, and 

 Actinoceras Bronn (= Ormoceras Hall). On Hyatt's review of the genera of Fossil 

 Cephalopods, see Proc. Boston Soc. Nat. Hist., xxii., 253, 1883. 



621-624. 



623. 



621. 



622. 



624. 



Figs. 621, 622, Bathyurus Saffordi ; 623, Bathyurellus nitidus ; 624, Bathyurus (?) crotalifrons. 



Billings ; 624, Dwight. 



FiL's. 0-21-623. 



6. Crustaceans. — Among Trilobites, Bathyurus Saffordi B. (Figs. 621,622) is com- 

 mon in Canada, and occurs also in Newfoundland and Idaho ; B. crotalifrons at Rochdale, 

 N.Y. ; B. armatus, Quebec and Saratoga County, N.Y. ; Ptychaspis speciosa, Ptychoparia 

 Calcifera, P. Hartti, are other Saratoga County species. Bathyurellus nitidus B. (Fig. 

 623) is from Cow Head, Newfoundland. None of these species occur in the Trenton. 



The Calciferous fossils reported by S. Calvin from the Lower Magnesian limestone of 

 Iowa are 3Ietoptoma alta Whitfield, Straparollus Glaytonensis Calvin, ^S*. pristiniformis 

 Calvin, Raphistoma Pepinense Meek, P. multivolvatum Calvin, Holopea turgida Hall, 

 Orthoceras primigenium V., 0. Luthei Calvin. 



2. Chazy Epoch. 



In the Chazy limestone occur small concretion-like forms (Fig. 625) hav- 

 ing the structure represented in Fig. 626, which are supposed by some to 

 be of vegetable origin, and by others, 



625. 



626. 



a Sponge or the secretions of Hydro- 

 zoans. 



The Corals of the period include 

 Cyathophylloids, a tribe that dates 

 from the early Cambrian ; massive 

 columnar Corals of the genus Colum- 

 naria; and species with quadrangular 

 cells, of the genus Tetradium — this 

 name, from the Greek for four, re- 

 ferring to the form of the cells (see 

 Fig. 707, page 511, for a Trenton 

 species). 



One of the Cystoids is represented in Fig. 628, and the body of a Crinoid 

 in Fig. 627. The stem is wanting in each. 



Fi" 



625, Girvanella ocellata; 626, interior enlarged. 



Seely. 



