225 



have tubercles, or, in some cases, spines on the rings. The pygidium has 

 a median tubercle on each of the first two joints, and the marginal spines, 

 of which only one pair is known, are directed outward rather than back- 

 ward. In other respects the two species, in so far as comparisons can 

 be made with the imperfect material obtained, are much alike. 



This species is distinguished from Protopeltura acanthura, var. tetra- 

 canthura* by the broad area in front of the glabella, and by its broader 

 pygidium with fewer joints. From Parabolina heres, var. lata^ it 

 differs in the arched anterior border fold, and narrow fixed cheek. From 

 P. here, as depicted by Brogger, it differs in its shorter pygidium of 

 fewer joints. { From P. acanthura, as figured by the same author, in 

 its more quadrate glabella, and in the tubercles on the rings of the rachis 

 of the pygidium. From P. heres, as shown by Moberg and Moller, in 

 the absence of strong reticulation on the surface of the fixed cheek, and 

 the fewer joints in the pygidium. || From P. acanthura, as figured by 

 these authors, in the arched front of the head-shield, and in the presence 

 of tubercles on the rachis of the pygidium.** 



From Parabolinella Plantii, Salter, as figured by F. R. C. Reed, it 

 differs in its arched front margin, broader glabella, differing glabellar 

 furrows, and in possessing pygidial spines.f f 



If it were not for the pair of marginal spines at the front corner of 

 the pygidium, this species, from the flattened side lobes of the pygidium 

 and other features, would fall under Brbgger's sub-genus Parabolinella. { J 



PARABOLINELLA? QUADRATA, PI. XVIII, fig. 7. 



Bull. Nat. Hist. Soc. of New Brunswick, vol. iv, p. 411, pi. xviii, fig. 7. 

 Middle piece of the head shield subtrapezoidal in outline. Anterior Paraboli- 

 marginal fold narrow ; width of the front area of the cheek, one-fourth drata. 

 of the length of the glabella. Glabella quadrate in front, and as wide 

 there as its length, but considerably narrower at the posterior furrow. 

 Posterior and second furrow directed backward, and deeply impressed in 

 the outer third, but not reaching the margin of the glabella. Eyelobe 

 slightly elevated, extending opposite the two anterior furrows of the gla- 



* Trans. Roy. Soc. Can., vol. ix, sec. iv, p. 53, pi. xiii, figs. 8a-c. 



fTrans. Roy. Soc. Can., vol. ix, p. 51, pi. xiii, figs. 6a-/. 



Die Silurish. Etagen 2 und 3, p. 101, tab. i. fig. 13d. 



Idem, p. 106, tab. 14, 14c. 



I! Om. Acerocarezonen, Stockholm, 1898, p. 267, tan. 12, figs. 8a, lla. 



** Idem, p. 259, tafl. 12, figs, la and 4a. 



ff Geol. Mag. New ser. dec. iv, vol. vii, p. 3G3, fig. 1. 



Jt Ibid new ser. dec. iv, vol. iii, p. 303. 



15 C R. 



