CAMBRIAN FOSSILS. 459 



CREPICEPHALUS Owen. 



Crepicephalus Owen, 1S52: Rept. Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 576, 

 PI. I, fig. 8; PL Ia, tigs. 10, 16, 18. Hall, 1863: Sixteenth Ann. Rept. New York 

 State Mus. Nat. Hist,, p. 147. Hall and Whitfield, 1877 : Rept. Geol. Expl. 40tn 

 Par., Vol. IV, Pt. II, p. 209. Whitfield, 1S76 : Rept. Reconnaissance from Oar- 

 roll, Montana, to Yellowstone National Park (Ludlow), p. 141. Whitfield, 18S0: 

 Rept. Geology and Resources of the Black Hills (Jenney), p. 341. Whitfield, 

 1882: Geol. Wisconsin, Vol. IV, p. 182. Walcott, 1884: Bull. U. S. Geol. Surv. 

 No. 10, p. 36. Walcott, 1886 : Bull. IT. S. Geol. Surv. No. 30, pp. 206, 207. 



Attention was called to this genus in 1886, 1 but in giving an entire 

 figure of C. texanus I will repeat the description given by Dr. Owen, and 

 also add a few remarks. 



Dr. Owen proposed the generic name Crepicephalus for some fragmen- 

 tary remains of trilobites, the characteristic features of the central portion of 

 the head of which he described, and he also gave figures of the associated 

 pygidia. The description of the central portion of the head is as follows: 



The rather flat slipper-shaped glabella is tapering and slightly acuminated 

 anteriorly, with a faint ridge in the median line; two small and very superficial 

 depressions, and a posterior faint furrow, very partially divide the glabella. The 

 facial sutures run nearly parallel to the margin of the glabella, and join a thickened, 

 cordlike, anterior narrow border, inclosing a convex area, narrower in front than at 

 the sides. Oblique plications can sometimes be traced on the cheek plate, in advance 

 of the eye, converging toward the apex of the glabella. 



In his remarks on the genus, he refers to figs. 10, 16, and 18 of PI. 

 Ia, as illustrating the central portions of the cephalic shield of the genus. 

 The comparison of these figures with typical specimens of Crepicephalus 

 (Owen's Dikellocephalus) iowensis shows clearly that the types of the genus 

 Crepicephalus should have been referred to this species. He also refers to 

 the associated pygidia which are illustrated by his fig. 8 of PI. I and fig. 16 

 of PI. Ia, a comparison of the pygidium of Crepicephalus iowensis with these 

 figures showing it to be identical. 



In the description of fig. 13 (PI. I) the species wisconsinensis is referred 

 with a (!) to the genus Crepicephalus. No reference, however, is made to it 

 in the text. Professor Hall, in referring to the genus, 2 speaks of this as the 

 only species designated by Dr. Owen, and states that it offers no distinction, in 

 regard to the head, from a species placed under the genus Lonchocephalus. 



1 Bull. (J. S. Geol. Surv. No. 30, pp. 206, 207. : Loc. cit., p. 147. 



