THE FAUNA OF THR ST. JOHN (iROUP. 115 



2. — CONOCOBYPHE ELEGANS. {Figs. 28-34.) 



Conocephalites elegans, Hartt. 



Prof. Hartt's account of this species is uot as full as that which he gives of Clenocepha- 

 lus Mattheivi, and a few words of additional description may be useful. 



CEPHALIC SHIELD. {Figs. 28, 29 and 34.) 



I find that, in shields which are not distorted, the occipital ring and spine project be- 

 hind the posterior line of the shield ; and that the posterior marginal fold overhangs the 

 furrow only in cases in which the shield is shortened by pressure. In the largest heads 

 the wide part of the anterior marginal fold is as much as the seventh of an inch (3| mm.) 

 in width. In flattened heads the glabella appears to be wider than it is long, but the rela- 

 tions are reversed when the natural form of the glabella is preserved, it being a little 

 longer than its width. The posterior marginal fold is thin, sharp and high in the inner 

 three-fifths, but broader and flatter at the outer two-fifths. Viewed horizontally, the fold 

 seems almost geniculated at the point where this change in width takes place; viewed 

 from above, the border is here sharply augulated forward. The occipital furrow is deeply 

 indented in the outer third, and arches back to the middle third, corresponding in its 

 course to the glabellar furrows. I do not find that the bounding groove of the glabella 

 joins the anterior marginal furrow, though it often has that appearance iu distorted heads 

 because the intervening space is low. I have seldom found an occipital spine more than 

 an eighth of an inch in length, including the slope of the ring, but the variation in the 

 length of the spine in Ctenocephahis Maltheivi would quite lead to the expectation that 

 longer spines may be found on some shields of this species. 



Facial suture. — This begins at the side of the head, where the marginal fold becomes 

 narrow, and usually at a point about as far from the front of the shield as the length of the 

 glabella ; it crosses the marginal furrow diagonally to the border of the cheek, along which 

 it runs for some distance, and then arches outward toward the posterior angle of the shield. 



Ocular ridge. — Prof. Hartt does not refer to this feature, and in some heads it is scarcely 

 distinguishable. It begins on the slope of the cheek, just behind the front of the gla- 

 bella ; there is no tuberculous elevation here, as in C. Baileyi, nor such a lenticular ridge as 

 in Ctenocephalus Mattheivi, birt the ridge is narrow and less elevated ; its extension crosses 

 the cheek more directly than iu the other two species, descending toward the point where 

 the facial suture, after cutting the anterior margin, curves in toward the cheek. The oc- 

 ular ridge and its ramifications are more distinct in the undersized and young of this 

 species than in the full grown trilobite. 



Sculpture. — There is more regularity in the arrangement of the tvibercles of this species 

 than in the mature Ct. Mattheivi. The row of tubercles, which in this species crosses the 

 glabella behind the first pair of furrows, consists of six, and arches forward on the slopes 

 behind the furrow. There is another row, also consisting of six tubercles, less arched 

 than the last, and terminating at the anterior ends of the same furrows. A more irregular 

 row of tubercules crosses the glabella on the space between the second and third furrows. 

 Between these three rows of tubercles, near the axial line, there is in each space a pair of 

 less prominent- tubercles. On some young heads the three principle lines of tubercles on 



