**? 



210 PALEONTOLOGY. 



than the breadth across the eyes, but generally a little naiTower, and the 

 antero-lateral angles are rounded by the extreme point of the movable 

 cheeks, which extend in front on the upper side of the carapace, while the 

 fixed cheeks are as a general thing reduced to their minimum breadth. 



Another feature which prevails throughout the entire group is the well- 

 marked, and often strong, ocular ridges, a feature rarely noticed among the 

 specimens from Wisconsin. The absence of this feature in these latter may," 

 however, be in great part owing to the unfavorable material and condition 

 of preservation, they being all casts in a loose, friable, and often coarse sand, 

 not fitted for retaining the more faintly marked characters of the organisms; * 

 while the matrix from these western localities is a hard and very solid lime- 

 stone, containing a considerable o mount of sand in some parts, and extremely 

 difficult to separate from the organic remains. 



The features above noticed are mostly those pertaining to Dr. D. D. 



Owen's genus Crepicephalus as shown in the figures, cited by him as generic 



(GeoL Iowa, Wis, and Minn., plate lA, figs. 10 and 18); and we see no 



sufficient reason why they should not be considered as of generic importance. 



But whether the name Crepicepliahis shall be retained is not so readily 



determined. The genus Loganellus Devine, 18G3, is a very closely allied, 



if not identical, form; but as no entire individuals have been obtained, either 



from the Wisconsin or these more western localities, except of C. (L.) Hagueij 



herein described, it is impossible to satisfactorily determine their true generic 



relations. There would seem, however, to be no doubt in regard to the 



generic identity of the latter, or of G. (L.) quadranSy with Loganellus Logani 



Devine, and from the great similarity of these to the dismembered parts of 



the other species, we are inclined to consider them as all pertaining to one 



genus. 



Crepicephalus (Loganellus) Haguei n. sp. 



Plate ir, figs. 14-15. 



Body broadly ovate in form, widest across the base of the head, 



broadly rounded in front and rapidly tapering behind to the small pygi- 



dium, strongly trilobed and moderately convex. 



* Since tins raatter bas beeu in the priuters' Lands, 1 have exaniincd many Ireshly 

 collected specimens frora several localities of this formation iu Wisconsin, and find, on 

 mast of them, the ocular ridges strongly marked. — 11. P. W. 



