SHUMARD — NEW FOSSILS. 103 



curved, diverging spines; axis and lateral lobes forming to- 

 gether nearly a semicircle — the former moderately elevated, 

 cylindrico-conical, bluntly rounded at extremity, as wide as 

 the lateral lobes; annulations four or five, rounded, separated 

 by narrow furrows — the first three sharply impressed, the last 

 nearly obsolete ; lateral segments four, well defined by the 

 lateral furrows — the first expanding a little towards the ex- 

 tremity, the second and third smaller and with margins near- 

 ly parallel, the fourth triangular. 



Length of head, 8 lines; length of glabella, 6 lines; width 

 of same at base, 5^ lines; width at apex, 3 lines. 



This species may be readily distinguished from the Crepi- 

 cephalus Wisconsensis, Owen, to which it is somewhat nearly 

 allied, by its wider and more conical glabella and much nar- 

 rower front margin. The pygidium (supposed by Dr. Owen 

 to belong to the C. Wisconsensis) is also very distinct from 

 that of the species under notice. 



After a careful investigation of Dr. Owen's figures in his 

 invaluable Report on the Geology of Iowa, Wisconsin and 

 Minnesota, and a study of specimens from the localities cited 

 by him, I am satisfied that the synonymy of this species as 

 above given will be found correct. 



The "(7. (Dikelocephalus?) lowensis was founded by Dr. 

 Owen upon the tail-shields of specimens from the Mississippi 

 opposite the mouth of Black river, and I am pleased that I 

 am able to add now to our knowledge of this interesting spe- 

 cies a description of the head. 



The genus Crepicephahis is not adopted, as it appears to 

 me notto differ materially from Conocephalites. Dr. Owen, 

 in his description of the genus Crepicephahis, refers evidently 

 to the existence of ocular ridges when he says that "oblique 

 plications can be traced on the cheek plate in advance of the 

 eye converging towards the apex of the glabella"; and I can 

 discern, also, obscure ocular ridges on one of my specimens of 

 C. lowensis. 



Geol. Pos. & Loc. — From the Potsdam (Primordial) Sand- 

 stone of the Bluffs of the Mississippi near the mouth of Black 

 river, Wisconsin. 



Conocephalites Wisconsensis, Owen sp. 



Ceepicephalcs (?) Wisconsensis, Owen. Geol. Rep. Iowa, Wisconsin and Minnesota. 

 Tab. 1, fig. 8 & 13, and Tab. 1 A, fig. 16. 



This is a well marked species, and readily distinguished 

 from the preceding by its glabella, which is proportionally 

 narrower and longer, while the sides are subparallel and al- 

 most as wide at apex as at base. The front border of the 

 head is also double the width of that of C. lowensis, and, ac- 



