TRENTON CONGLOMERATE OP RYSEDORPH HILL 55 



rior margin nearly straight, lateral margin only slightly convex 

 and curving but little inward to the base of the broad frontal 

 lobe, which has straight margins, tapers only slightly and has a 

 nearly straight frontal edge. Glabella moderately and regu- 

 larly convex, highest at base of frontal lobe, from which it slopes 

 regularly to the posterior and lateral margins and falls abruptly 

 forward. Frontal lobe about one third the length of the crani- 

 dium. Glabellar furrows probably indicated by two pairs of 

 barely visible, low, broad undulations near the posterior lateral 

 margin, but not by smooth lines. Palpebral lobes very narrow, 

 abruptly bulbous at the posterior angle. Surface of the crani- 

 dium smooth to the unaided eye, but not glossy on account of 

 the presence of a microscopically small granulation; no striae 

 observable. Occipital ring rather broad and wide, partly exfol- 

 iated in the type specimen. 



Dimensions. Width of cranidium 9.6 mm; length to base of 

 frontal lobe 7.9 mm; hight 3.2 mm. 



Horizon and locality. In the reddish gray hard limestone peb- 

 bles at Rysedorph hill. (Group 6) 



Observations. The glabella of this form shows a slight simi- 

 larity in outline to that of R. striatulus Walcott, from the 

 upper third of the Trenton limestone; it differs, however, by the 

 absence of the coarse tuberculation and the suppression of the 

 glabellar furrows, of which at least one pair is distinguishable in 

 that species by smooth lines. 



The cranidium appears to be more closely related to R e m o - 

 pleurides c o 1 b i i Portlock, from the Caradoc, than to any 

 other congener, but has also some relationship to R. a f f i n i s 

 Billings, from the Quebec group. 



Salter, proposed to subdivide Remopleurides into two sections : 

 one without glabellar furrows and inflated glabella, for which 

 Portlock's original term, Remopleurides, was retained, and one 

 with glabellar furrows and flat glabella, for which Barrande's 

 name, Caphyra, was proposed. 



