90 ROYAL SOCIETY OF CANADA 



ol' the crusl, and is j)rovidc'd with a singk' rin^' ; axis narrower than the 

 lateral lobes, rings seventeen, each of which is separated by a groove 

 about as wide as the rinj^s. 



''Axis armed by a row of sharp spines ; hiteral lobes provided with a 

 row of tubercles or prominences along the median line ; margins of the 

 rib-groove I'un parallel as far a-s the tubercle, then they diverge ; tubercles 

 become obsolete toward the tail ; caudal shield very small, provided with 

 one or at most two rings." 



Emmons's statement of the course of the facial suture, would conform 

 to the course of that seam in Ptychoparia, but not in Conocoryphe, and 

 Walcott distinctly says that the course of the suture in the tirst type 

 specimen is that of Ptychoparia ; ' but there must be some confusion here, 

 for neither in the first nor second type figured by Walcott is any such 

 suture shown.- 



The suture in Emmons's species as in Conocoryphe, sens, strict., cuts 

 off a portion of the depressed part, or marginal furrow of the cheek. The 

 anterior end of the sutures cuts the frontal limb of the shield into three 

 equal parts (exclusive of the genal spines). The anterior part of the 

 limb between the sutures is sharply upturned and nearly straight across. 



The genal spine is quite short, and not quite terminal because the 

 posterior margin of the cheek turns forward toward the outer angle. 



Emmons states that the axis of the thorax is narrower than the 

 pleui-5ti, this holds for the posterior pleura?, but the middle are as wide as 

 the axis and the anterior are shorter than it. 



The geniculation of the pleurae to which Emmons refers as a row of 

 tubercles, is nearer the distal end in the anterior pleura^, but nearer the 

 rachis in the others. The anterior pleura* are obtusely pointed, but the 

 others bear short points directed backward. 



Though Emmons figured the ocular crest he appears not to have 

 noticed it in his description. It differs from that of other sections of the 

 genus Conocoryj)he in being set far forward, greatly shortened, and more 

 prominent than usual ; from its rough almost tuberculated summit, several 

 strong ridges descend the anterior slope toward the front margin. 



The Newfoundland specimen does not show the sharp genal spine 

 directed backward, which Walcott delineates, but a short blunt point 

 directed outward. They are more like those of the young example figured 

 by that author.* 



Sculpture. — The surface ornamentation is as described by Emmons, 

 the tubercles being largest and most prominent on the glabella and the 

 rachis of the thorax. 



>S«2e.— Length of the head-shield 14 mm., width 32 mm. Length of 

 the movable cheek, including the genal spine 16 mm. ; width in the 



' U.S. C.eol. Surv., Bull. 'M, p. 204. 



* IVjid. pi. xxvii, llga. 1 and Ir. 



' OlenelluH Fauna, pi. xcv., figs. 56. 



