Vol I. Grahau — Ordovician Fof^sih from North China (i) 15 



species. The Mingan Islands in the Gulf of St. Lawrence nortli of Anticosti Island, are 

 composed of Ordovician strata, l)Oth Beekmantown and Chazy being present, while 

 Potsdam sandstone (possibly only a basal sandy phase of the Beekmantown rather 

 than true Postdam) occurs on the mainland to the north. A minganense and A. 

 chihliense thus appear to be the last siu'vivors of the Archseocyathinte, which continued 

 into the Lower Ordovician. Our species has a proportionately thicker thecarium than A. 

 iiiingcmeiisc, while the arrangement of tlie septa in groups of 4 or 5 further differentiate 

 it from the American species. The strong annulations and nodes characteristic of the 

 latter, are not developed in the Chinese form, or only slightly so. 



Horizon and Locality: This species was collected by Dr. F. F. Mathieu from 

 the Peilintze limestone of Pei-lin-tze, Shih-mun-chai region eastern Chihli province, at 

 horizon No. 1. It is associated with (Jj>luleta squamosa, Cu'incroceras and Chihlioceras. 

 The ago is Lower Ordovician. 



Class BRACHIOPODA 



Order Protremata Beecher 



Family ORTHID^E \\"oodward 



Genus ORTHIS Dalman 



(Bincnd. Hall and Clarke) 



Orthis calligramma Dalm. 



var. orthambonites von Buch (de Verneuil) 



Plate ]. Figs. 4a - c, 5a - d 



1827 Orthis calligramma Dalman, Kon. Vet. Acad. Handl. p. 114, pb 2 fig. 3. 



1845 Orthis calligramma de Verneuil, in Murch. De Vern. ct Kayserl. Geology of Russia and 

 the Ural Mountains, Vol TI, p. 207, plate XIII, figs. 7a- 7f, and var. orthambonites yon Buch, 

 ibid. figs. 8a - 8g. 



1868 Orthis calligramma Davidson, British Silurian Brachiopoda (PahTontographical Society Mono- 

 graphs), p. 240, pi. XXXV figs. 1 - 17 (Bibliography and synonymy). 



1883 Orthis calligranuna Kayser, in Richthofen, China Vol. IV, p. 40, pi. Ill, figs. 10- 13. 



1901 Orthis calligramma var. scrica Martelli, Boll, della Soc. Geol., Ital. vol. XX, p. 297, pi. 4, 

 figs, 1-4; var davidsoni Martelli, idem. p. 301, pi. 4-5, figs. 5 - 6. 



1913 Orthis calligramma Weller, in .Willis, Research in China, vol. Ill, p. 282, pi. 2-3, figs, 3-6. 



