238 ROYAL SOCIETY OF CANADA 



ward arching of the concentric lamination of the surface at the centre 

 of the sinus. On the fold of )3rachial valves (see figs. 2, 7, 6, and 8) a dis- 

 tinct medial sulcus runs along the centre of tlije fold, which is broad at 

 the front. 



The plications are crossed by fine concentric lines (PI. IV, fig. S) 

 and a few stronger lines of growth, but not so strong or prominent as in 

 typical cases of Sp. yennatus, as was noted by Dr. Ami. 



Although the sinus of the pedicle valve is not juiafked by a pro- 

 minent median plication the presence of a slight plication is seen which 

 does not rise much above the bottom of the sulcus, and a backward arch- 

 ing of the concentric lines on the surface is observed in some specimens 

 a character which distinguishes Sp. pennatus from *S'. macra in which 

 the sulcus is smoothly rounded and the surface lineations are without 

 inter;niption across the bottom of the sulcus. In this respect the speci- 

 mens are interpreted diffetrently from the description given by Schuchert 

 above. The sulcus in the middle of the brachial fold is quite deep and 

 broad toward the front and extends from beak to front. 



8p. Heïenœ differs from S. paradoxus, Schlothemi, by having its 

 plications finer and not so oblique (see Freeh., Leth. geog., plate 33a., 

 fig. lb), and the species appears to be normally smaller than that species. 



The Côte St. Paul and upper St. Helen's species is evidently a 

 mutant of the form called Sp. gaspensis by Billings, and forms the link 

 between it and Spirifer pennatus of the Marcellus and Hamilton forma- 

 tion of the Middle Devonian. The above definitions are based upon a 

 fine) series of specimens from the loose blocks obtained on the island of 

 Montreal near Côte St. Paul. They appear to be identical, however, with 

 the " long winged spirifer," from the " flat block of limestone in which 

 are the long spirifer " of the St. Helen's breccias, called 252.1 in our 

 list and collected by Mr. Ardley. A minute comparison with the original 

 specimen's in the collection of McGill College shows them to be identical 

 in the characteristics distinguishing this new variety Sp. pennatus var. 

 Heïenœ. 



This variety is referred to particularly in a lislj of the species from 

 the St. Helen's Island breccias made by H. M. Ami and published in 

 1894 in the Ann. Eept. of the Canadian Survey^ in the following words : 

 " 28. Spirifera, sp. with from 18 to 20 costœ on each side of the mesial 

 simis. General appearance very much like S. pennata (= S. mucro- 

 ndta), not quite so arcuate and the concentric lines of growth are not 

 so strongly lamellose or rugose." 



1 Ann. Rept. Geol. Surv. Canada, Vol. VII, new series, p. 155J, Ottawa, 1896. 



