AST. 21 ORDOVICIAN TRILOBITES ULRICH 23 



of the four anterior spines appear larger than the inner pair in 

 dorsal view. 



Comparisons with T. granulatus Angelin, founded on Swedish 

 specimens, are given in preceding remarks on that species. 



The larger of the two cranidia of this species now available, 

 namely the one regarded as the holotype, shows some obscurely de- 

 fined shallow depressions on the lateral slopes of the glabella. These 

 suggest imperfectly developed glabellar furrows or dimples as occur 

 in T. hipy/nctatus and T. mohevgi. The second cranidium lacks 

 these depressions and differs further from the holotype of the species 

 in the more conical form of its glabella and in the greater width of 

 the fixed cheeks. As it approaches T. prattensis in these respects it 

 is provisionally distinguished as var. simulator. 



Strangely, the preparation of our collections from Mystic revealed 

 more than 10 free cheeks but only 2 cranidia and 2 pygidia. These 

 cheeks are readily distinguishable from all others so far observed. 

 The eyes, as usual, constitute by far the greater part of the cheek, 

 but they are uncommonly bulbous and very finely facetted. Another 

 peculiarity is that the thin rim carries no spine, only widening and 

 the outline becoming obtusely angular at a point slightly behind the 

 middle of the compound eye. Slight differences were noted in com- 

 paring these cheeks. In one set (figs. 3, 4), supposed to belong to the 

 typical form of the species the eye is slightly longer, the rim wider 

 and more sharply curved at the genal angle, and the anterior edge of 

 the eye more distinctly overhangs the very thin anterior rim of the 

 cheek than in the other set which is supposed to belong to the variety. 



Two pygidia referred to this species agree in segmentation and 

 general character fairly well with the pygidium ascribed to T. frac- 

 ius by Barrande. However, they are longer and more quadrate or 

 rather pentagonal than triangular and terminate posteriorly in a 

 sharp angle or short spine and show a pair of still blunter projec- 

 tions at points nearly midway between the median posterior spine 

 and the antero-lateral angles. 



OccuiTence. — From a highly fossiliferous limestone boulder sup- 

 posed to be of Blount, or at least Chazyon, age in the conglomerate 

 near Mystic, in the southwestern corner of the Province of Quebec. 



Eolotypes of species and variety. — Cat. Nos. 80526, 80527, U.S.N.M. 



TELEPHUS BICORNIS. new species 

 Plate 4, Figures 1-14 



As shown by the illustrations the cranidium of this species agrees 

 rather closely in all save one conspicuous feature with the cranidia 

 of T. pustulat'iis.) T. geladnosus, and one or two others of the numer- 

 ous American species here described. The distinctive character re- 



