46 ROYAL SOCIETY OF CANADA 



COXOUEPIIALITES, Barraiide. 



CONOCEPHALITES (C^NASPIS ?) cf. PERSEUS, Hall. (PI. II., fig. 4.) 



cf. ConocephaliteH (Conasjiis) perseus. Hall, Preliminary notice of the Fauna of 

 the Potsdam Sandstone, Albany, 1862. 



In a small head that occurs in these shales, we seem to have an 

 example of the genus Coiiocephalites (sens, strict) ; that is, species which, 

 with a long conical glabella, have narrow fixed cheeks and a long eye- 

 lobe. Trilobites of this type were found by Barrande in the Fauna of 

 Hof. (C. Wirthi and C. Bavaricus), by Hall in that of the Potsdam Sand- 

 stone of Wisconsin (C. perseus, C. lowensis, C. anatinus) and by Brogger 

 in Norway, C. ornatus. 



The present example may be that of an immature individual, but as 

 it introduces a new type into this fauna, it is worth describing. 



Only the middle piece of the head-shield is known. This is sub- 

 quad i-ate, but with the posterior angles much extended. 



The anterior marginal fold is narrow and the lateral angles are 

 truncated as in Couaspis, Hall, the area in front of the glabella is 

 about twice as wide as the fold, and the dividing furrow is sharply 

 impressed. The glabella is elongate-conical — about a third longer than 

 wide, impressed by three pairs of furrows, the posterior quite oblique 

 an J almost meeting the occipital furrow ; the second pair, also oblique, 

 but shorter, the third pair quite short and close behind the inner end of 

 the ocular fillet. The occipital ring is three times longer than \vide, 

 separated from the glabella by a distinct furrow, sharply impressed in the 

 outer third. 



The fixed cheek opposite the eye-lobes is narrow, scarcely wider than 

 half of the width of the glabella at the back, but at the posterior lateral 

 angles it is more than the width of the glabella ; the e3''e-Iobe is as long as 

 the width of the glabelhi in front, with which it is connected by a strong 

 ocular fillet ; the dorsal furrows are deep and meet in front of the 

 glabella. The dorsal suture goes nearly directly forward in front of the 

 eyes, but behind the eyes, curves sharply outward. The posterior margi- 

 nal furrow is narrow, and is geniculated at the middle. 



Sculpture. — The surface of the test is minutely granulated, and 

 obscure ridges radiate from the front of the glabella and ocular fillet 

 toward the anterior margin of the shield. 



Size. — Length of the head, 5 mm. AVidth of the middle piece, in 

 front, 4 mm. ; behind, 7^ mm. 



A species not very difterent from this in form of the middle piece of 

 the head, is the Conocephalites (Conaspis) perseus, of Hall, found in the 

 Potsdam Sandstone of Wisconsin. It has a narrower and more pointed 

 front, broader glabella and less oblique furrows on the glabella, as well as 



