THE FAUNA OF THE ST. JOHN (iKOUP. 79 



described chiefly in the following particulars : — The glabella is larger in proportion to the 

 other parts of the shield between the sutures ; the anterior marginal fold is narrow in 

 front and wider at the ends, and the extremity, including the suture as far as the eyelobe, 

 is more broadly rounded ; the anterior angle of the suture approaches more closely to the 

 glabella, which is larger and more tumid in the anterior half; the eyelobe and fixed cheek 

 are proportionately smaller, and the posterior extension of the facial suture is shorter. 



Free cheeks. The remains of this part of the test, which have so far been recovered, 

 are not sufficient for a proper description. It may be said, however, that this species had 

 long, slender genal spines, which were round and sharply pointed. The shell substance 

 was thin, so that when flattened in the shale the spines i^resent numerous transverse 

 fractures that have the appearance of annulations or partitions. 



The hypostome has the doubleur attached, and its width is about two fifths greater 

 than its length. The doubleur is arched around the front of the large lobe of the hypo- 

 stome which projects into it, narrowing it at the apex to little more than a third of its 

 width at the extremities. The large lobe of the hypostome is transversely rhombic. The 

 posterior end of the hjqiostome is subc^uadrate, with A^ery short spines near the outer 

 angles ; there is a narrow lobe at this end of the hypostome which crosses it transversely, 

 and extends forward on each side of the posterior extremity of the large lobe. 



The pygidium is rectangular, with a deep and rather angular sinus at the extremity. 

 The width is three cjuarters of the length ; it is of nearly ecjual width from the front for 

 more than two thirds of its length, and then narrows to two subcuspidate points. The 

 axial lobe is about three fifths of the whole length of the pygidium, and about two thirds 

 of its Avidth ; it is cylindrical for half its length, and then regularly rounded to the 

 extremity ; it has two rings, of which the anterior is most distinct ; and there are two 

 other rings, indicated by faint furrows on the posterior lobe ; the last of these rings is quite 

 obscure. A depression, fiding out toward the extremity of the pygidium, separates the 

 axial lobe from the lateral lobes, which have no conspicuoiis features. 



A pygidium very like this in general form, but lacking the cuspidate points at 

 the extremity, is perhaps that of the broad form of this species ; in it the axial lobe is 

 more prominent and more triangialar than in that described above, and the posterior mar- 

 gin has an oval outline. 



Sculpture. The anterior marginal fold of the cephalic shield is marked by a few par- 

 allel raised lines that disappear successively from the upper surface on each side of the 

 apex over the folded front of the shield, so that the back of the fold and its outer ends are 

 smooth. The front two thirds and both sides of the dome, or three front glabellar lobes, 

 are ornamented with short interrupted raised lines, rudely parallel to the periphery of the 

 dome, and somewhat distantly placed. Numerous small tubercles are distributed over the 

 surface of the occipital ring, and are most numerous on the middle third ; similar tuber- 

 cles, but smaller and more widely separated, are found on the surface of the first lobe 

 of the glabella, and iuA'ade the dome upon the central part of the posterior third, o\qv 

 which they are sparsely scattered. One or two irregular tows of similar tubercles may 

 be observed along the oiiter border of the eyelobe, and tubercles may also be seen scattered 

 over the surface of the fixed cheek, which has a scabrous surface. The posterior marginal 

 fold has a few tubercles scattered along its siirface. 



The decoration of the hypostome is varied. The doubleur, or fold in front, has about 



