Vol I. Grabaii Ordovician Fossils from North China (i) 15 



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

 composed of Ordovician strata, both 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. 

 cliiltlinixt' thus appear to be the last survivors of the Archseocyathinse, which continued 

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

 iiiitHjuncnse, while the arrangement of the 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. I. It is associated with Ophileta squamosa, Camcroceras and Chihlioceras. 

 The age is Lower Ordovician. 



Class BRACHIOPODA 



Order Protremata Beecher 



Family ORTHIDyE Woodward 



Genus ORTHIS Dalman 



(Emend. Hall and Clarke) 



Orthis calligramma Dalm. 



var. orthambonites von Buch (de Verneuil) 



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



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



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

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

 ibid. figs. 8a - 8g. 



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

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



1883 Orthis calligramma 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 daridsoni Martelli, idem. p. 301, pi. 45, figs. 5-6. 



1913 Orthis calligramma Weller, in Willis, Research in China, vol. Ill, p. 282, pi. 25, figs, 3-6. 



