cieB of coral, one of whioh has already been partially described by Dr. 

 H. A. Kicholson, on pages 66 and 6Y of bis report on the Palaeontology 

 of Ontario for 18*75, as follows : 



" The Guelph Limestones contain in abundance a species of coral, 

 which I am unable to refer with certainty to its proper genus. Some 

 specimens have the form of detached cylindrical tubes, irregular in 

 their thickness, but varying in diameter from a line and a half to three 

 lines. These tubes are ilexuous, and fm-nished both with very well 

 developed tabulas, and with marginal septa in the form of strong longi- 

 tudinal ridges. Examples of this kind present precisely the characters 

 of the genus Anvplexus, and I have been under the impression that they 

 were referable to Amplexus laxatus, of Billings, a form which is quoted 

 in the " Geology of Canada," as occuring in th,e Guelph Limestones, 

 but the description of which I have been unable to consult." 



"Other specimens, equally or more abundant, consist of numerous 

 closely approximated tubes, similar in their structure to the above, 

 and apparently forming part of a composite mass. This would lead one 

 to separate these specimens from Amplexus, which contains only simple 

 forms ; but one would still be left uncertain where to place them. The 

 genus to which such specimens are referable by their general form and 

 mode of growth is Diphyphyllum ; but they differ from this genus and 

 agree with Awplexus, in the presence of complete tabulae, (not a mere 

 central tabulate area), and in the rudimentary condition of the septa. 

 The same form occurs in the Corniferous Limestone, but I must at pre- 

 sent leave its position unsettled." 



Ptcnostylus Guelphensis. (]Sr. Sp.) 



Plate 1, figs. 1, la & lb. 



? Amplexus laxatus, Billings. 1863. " Geology of Canada," pages 340 & 342, but 



with no description nor figures. 

 Amplexus (?) sp. Nicholson. 1875. Palaeontology of Ontario, p. 66. 



Corallites long and slender, averaging from three to seven milli- 

 metres in diameter, and dividing uniformly at the same point into either 

 three or four branches. Epitheca marked by transverse constrictions 

 and re-elevations at irregular distances, but not longitudinally ribbed. 

 Primary septa alternating with smaller secondary ones. 



ISTew Hope, E. Billings, 1857 : Guelph, E. Bell, 1861 : Hespeler, T. 

 0. Weston, ISGT : Elora, Mr. D. Boyle, 1880 : Durham, Mr. J. Town- 

 send. 



A common and characteristic fossil of the Guelph Formation, to 



