The two 

 Canadian 

 varieties 

 contrasted. 



222 



seems to be greater ; it appears also to show that the American mutations 

 arose independently of the typical forms, from the Longifront phylum. 

 The indication is similar to that given by the development of Anomocare 

 stenotoides from the Olenoid phylum, i. e. } & tendency to the independent 

 development of similar forms at particular stages in geological history.* 



The differences of mut. germanus from A. trisectus-ponepunctus, are 

 the following. The head-shield is more strongly arched, stiffer and 

 smoother; the pygidium is not trisected on the posterior lobe of the rachis, 

 thought faint furrows may sometimes be traced on one side or the other. 

 It differs from the European type of triseclus, in that the median lobe tra- 

 verses the middle part of the two anterior segments, thus interrupting 

 the dividing furrow between these segments, and it differs also in its 

 smooth, stiff shields. 



This mutation shows a considerable resemblance to A.princeps, Salt. { 

 But Salter is emphatic in stating that there are no marginal spine (never- 

 theless two of these figures show such spines, (perhaps there are two 

 species included under A. princeps). The figure of Salter's species which 

 comes nearest ours is 16 of plate 5, but in that the tubercle on the gla- 

 bella i^ represented as elongated and resting on the middle of the main 

 lobe, while iti the Cape Breton form it belongs entirely to the anterior 

 segment or somite of the main lobe. 



Agnostus of. 

 cyclopyge. 



AGNOSTUS, cf. CYCLOPYGE, Tullberg. 



cf. Agnostus cydopyge, Tullb. Sverig. Geol. Undersok, Ser. C. No. 42, p. 



26, table ii, fig. 15c. 



A single pygidium that corresponds to Tullberg's figure of this species 

 was found in association with the other trilobites of the Peltura Fauna 

 at Escasonie. The posterior lobe of the rachis is quite obliterated, not 

 even showing the little grooves on each side of the front of this lobe, 

 shown in Tullberg's figure. 



Sizq. The example is small, not more than two-thirds of the length 

 of the typical form. 



Horizon and locality. In a thin limestone of Band C 3b at Escasonie 

 shore East bay, N.S. 



* See. Trans. Roy. Soc. Can. vol. iv, sec. iv, pp. 140-148. 



t Mem. Geol. Surv. G. Britain [vol. iii, p. 488, pi. 4 figs 2 and lla, and pi. 5, figs, la 

 and b. 



