Contributions to Palozontology. 159 



" Length of head, 0-22 of an inch ; length of glabella, 

 " 0-16 ; greatest width, 0-11. The general contour of 

 " the head of this species, when deprived of the mova- 

 " ble cheeks, reminds one of the head of Homolonotus 

 " delphinocephalus." 



Through the kindness of Dr. Shumard, I have received speci- 

 mens of this pretty little species. In the form of the glabella, it 

 resembles some of the smaller species of Conocephalites; but the 

 direction of the facial suture, and the form of the palpebral lobe, 

 are distinguished features. At the same time, the form of the 

 associated movable cheeks is not unlike many of those which occur 

 with, and are referred to the smaller species of Conocephalites, 

 while the fragments of thoracic segments are likewise of similar 

 character. 



The minute depressions, or puncta, at the anterior angles of the 

 glabella, are well preserved in many specimens, while the occipital 

 ring often bears a small obtuse spur. The minute pits in front of 

 the glabella are well marked; but these are not peculiar to this 

 species. 



I follow Dr. Shumard in placing this species under Arionelltjs, 

 though it appears to me distinct from that genus, and not generically 

 different from some of the preceding species. 



From the associated fossils, I infer that this species occurs about 

 the middle of the sandstone, " near the mouth of Lawrence creek, 

 a small tributary of the St. Croix river, Minnesota ; and from the 

 mouth of Root river in Minnesota, in the same horizon. 



In his Report on Wisconsin, Iowa and Minnesota, Dr. 

 Owen has described (on pp. 374 & 375) the Dikeiocephalus 

 miniscaensis and D. granulosus. From specimens collected 

 at the same localities, I have recognized these species so 

 distinctly as to leave no doubt of their identity. "While 

 possessing some characters of glabella in common with 

 typical species of Dikelocephaltjs, there are other features 

 which appear to me quite incompatible with that genus. 

 The fixed cheeks are wider, and the facial suture has a 

 different direction, while the movable cheeks are equally 



