112 CONTRIBUTIONS TO CANADIAN PAL/EONTOLOGY. 



approaches also in shape to the oval variety of L. punctata represented 

 by figure 6 f of plate 1 of the first part of the fourth volume of the 

 " Paleontology of the State of New York," but is broader in proportion 

 to its length and its surface is not punctate. 



Productella (Strophalosia?) truncata, Hall. 

 Plate 16, figs. 1 and 2. 



Prodiictus truncatus, Hall. 1857. Tenth Eep. N. York St. Cab. Nat. Hist., p. 171. 

 Strophornena pmtulosa, Hall. 1843. Geol. Kep. 4th Distr. N. York, p. 189, fig. 4, 



"but not Productus pustulosus, Phillips. 

 Productella truncata, Hall. 1867. Pal. State N. York, vol. IV., pt. 1, p. 160, pi. 23, 



figs. 12-24. 

 Productus {Productella) truncatus, (Hall) Walcott. 1884. Pal. Eureka Dist., p. 131, 



pi. 14, fig. 2. 



Bartlett's Mills, near Arkona, and near Thedford in the town- 

 ship of Bosanquet, Eevs. Hector Currie and .T. M. Goodwillie, 1882 : a 

 few specimens which are referred to this species solely on the authority 

 of Prof. E. P. Whitiield. 



As compared with Professor Hall's description and figures of P. 

 trancata, however, these specimens seem to differ materially in their 

 far less convex ventral valves, (which j-esemble Lepfmna or Chonetes 

 in this respect rather than Productus or Productella, whose umbones are 

 not at all prominent, and neither broadly nor distinctly troncated. It 

 is diflicult to see how the specimens from Arkona and Thedford are to 

 be distinguished from some forms of the Strophalosia productoides of 

 Murchison, especially fi-om such as are represented on plate 19, figures 

 15, 16 and 19 of Dr. Davidson's monograph of the British Devonian 

 Brachiopoda. 



In 1882 several good examples of >S'. productoides were collected by 

 Dr. E. Bell from rocks apparently of about the age of the Hamilton 

 Formation on the Athabasca Eiver in the first ten miles below the 

 Clearwater, the most perfect of which is represented, for comparison, 

 on Plate XV. This beautiful fossil was compared by Dr. Davidson 

 with authentic English and European examples of S. productoides and 

 pronounced somewhat confidently to be identical therewith (as the 

 writer had previouslj' supposed was the case) in the spring of 1883. 

 In the specimens from Arkona and Thedford the umbones are not so 

 prominent and the so-called pseudo-deltidium not so distinctly marked 

 as in those from the Athabasca, but these apparent difterences seem 

 largely attributable to the much greater size of the latter and David- 

 son's figures show that specimens from various localities in England 

 vary quite as much in both of these characters. 



