CONTRIBUTIONS TO PAL^ONTOLGGY. 145 



palpebral lobe nearly to the occipital furrow, when it turns 

 abruptly outwards. Dorsal furrow rather wide and deep, con- 

 tinuing a little less distinctly around the front. 

 Fixed cheeks narrow, expanding in the direction of the e3'e, and 

 separated from the palpebral lobe by a long distinct sigmoid 

 groove : posterior limb narrow, its extent unknown. Frontal 

 limb of moderate width, separated from the glabella by a 

 narrow groove, marked along the middle by a broad shallow 

 transverse furrow, which is stronger at the sides and sometimes 

 nearly obsolete in the middle; anterior margin flattened, and a 

 little produced in the middle. 



The characters here given are pretty constant in several speci- 

 mens : the prominent lobed glabella, broad dorsal furrow, and 

 narrow fixed cheeks, are distinguishing features. The posterior 

 glabellar furrows are sometimes continued in a slight depression 

 across the centre. The frontal limb is sometimes, but not always,' 

 a little produced in the middle, and a shallow furrow is always 

 percijptible. 



A well -formed specimen gives the following measurements: 

 Length of glabella, 0*30 of an inch; width at base. 0'29 ; width 

 at apex, 0*22; frontal limb, 0*12 ; entire length of head, 0-48. 



A pygidium in the same assopiation, and apparently belonging to this 

 species, has the anterior margin much curved, the axis very prominent, and 

 the lateral lobes convex near the axis, concave and flattened towards the 

 margins. The axis is marked by four annulations, exclusive of the anterior 

 ridge : the posterior one is elongate, and apparently indented about the 

 middle of its length. The lateral lobes have three or four ribs, which are 

 longitudinally divided, and terminate in a flattened border : the divisions 

 are narrow and prominent. 



In species like this one, it is not easy to point out the characters which 

 separate them from such forms as DikeJocephalus apiniger or D. pepinensis; 

 and we have the features of glabella intermediate between the more cha- 

 racteristic forms of CoNOCEPiiALiTES and Dikelocephalus. In this one 

 the glabella is more conical, and the posterior glabellar furrows scarcely 

 united across the summit. 



The pygidium which occurs in several specimens associated with the 

 glabella, has the prominent axis and broad lateral lobes with wide margin 

 which are characteristic of the Dikelocephalus, and I am therefore in- 

 duced to place the species under that genus. 



This species occurs in the second fossiliferous beds at Trempaleau, and 

 in the greenish sandstone near the same horizon at Miniska, about the 

 middle of the formation. 



[Senate, No. 11 5. J Id 



