CANADIAN PALEOZOIC CORALS. 



129 



primaries and secondaries. No dissepiments. Septal fosette present. 

 Differs from Zaphrentis only in the feeble development of the septa. 



Type species. — A. coralloides, Sowerby. 



Range. — Silurian, Devonian, Carboniferous. 



Amplexus cingulatus, Billings. 

 Plate X., figs. 2 and 3, 3a. 

 Amplexus cingulatus, Billings. 1862. Palaeoz. Foss. vol. 1, p. 106. 



11 Corallites very elongate, cylindrical, varying from 3 to 8 lines in 

 diameter, annulated at various distances by prominent usually sharp- 

 edged rings of growth, with concave spaces between. Radiating septa 

 from fifty to eighty, according to the size of the corallite, extending in- 

 wards about one-sixth of the diameter. The inner area occupies fully 

 five-sixths of the whole diameter ; the transverse septa or tabulae thin, 

 slightly undulating, from J to f of a line apart. Surface with about two 

 longitudinal septal striae in one line, the ridges between which are often 

 divided by a smaller stria. 



"The annulations are distant from each other from 2 to 14 lines, the 

 most common distance being about haif an inch. They are usually sharp- 

 edged, but often in the younger corallites they are either obtusely round- 

 ed or represented by mere enlargements of the diameter of various forms 

 and distances. 



" This species appears to be gregarious, as great numbers are found on 

 the same slabs of limestone, lying across each other in all directions and 

 broken into fragments from 1 to 4 inches in length." (Billings.) 



Localities. — L'Anse a la Barbe, Baie des Chaleurs, Que., Silurian*; col- 

 lected by Sir William Logan, 1843, and also at l'Anse au Gascon, by R. 

 Bell, in 1862. 



*In the "Geology of Canada, 1863," it is said (p. 933) of the limestones, exposed on the 

 coast of the Baie des Chaleurs in the vicinity of Anse a la Vieille, Anse au Gascon and 

 Anse a la Barbe, that they "contain a fauna, which is, upon the whole, distinct from 

 that of the Niagara and Guelph formations on the one hand, and from that of the Lower 

 Helderberg on the other ; while at the same time it is more closely allied to the fauna 

 of the Ludlow group of England than any other yet discovered in the Silurian rocks of 

 America. It (the Upper Silurian of the Baie des Chaleurs) seems to occupy a position 

 between the Niagara and the Lower Helderberg, but to be more intimately connected 

 with the former than with the latter. " In a table of probable equivalents among the 

 Palaeozoic rocks of Great Britain and North America included in the above work the 

 " limestones of Gaspe and the Baie des Chaleurs " are placed in the same column with the 

 " Lower Helderberg group " of New York and the " Ludlow Group " of Great Britain. 

 In the " Palaeozoic Fossils," vol. III., pt. I., Dr. Whiteaves states that in his opinion the 

 limestones of Anse a la Barbe and Anse a la Vieille seem to be most nearly equivalent to 

 the Guelph formation of Ontario, Ohio and Wisconsin. In part I., of volume IV, of the 

 " Contributions to Canadian Palaeontology " the term Lower Helderberg has been used 

 in connection with the Baie des Chaleurs limestones at Anse a la Barbe, &c, in a sense 

 as comprehensive as that evidently implied by the term in the " Geology of Canada." 

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