10 



ARTICULATA. 



TKILOBITA. 



CALYMENnm 



GENUS CREPICEPHALUS, Owen (?LOGANELLUS, D 

 CREPICEPHALUS (LOGANELLUS) CENTRALIS, n. s}). 



Plate 2, figs. 21-24. 



Species recognized only by the glabella and fixed cheeks, with a few 

 imperfect fragments of the movable cheeks. The former parts, when 

 united, are somewhat quadrangular in outline, broadest at the base and 

 gently narrowing in front ; glabella rounded-conical, higher than wide, 

 the anterior end somewhat sharply rounded ; surface highly convex and 

 marked by three pairs of distinct lateral furrows, which are strongly 

 bent backward in their direction from the margin, and on the larger 

 specimens the posterior pair almost unite in the middle. Occipital fur- 

 row distinct, extending entirely across the base of the head ; occipital 

 ring strong, rounded, and in the older individuals supporting a short 

 spine; dorsal furrows well pronounced, extending with equal clearness 

 in front of the glabella. Fixed cheeks broad, more than equaling one- 

 half the width of the glabella; palpebral lobes small and slightly angu- 

 lar, situated opposite the middle of the glabella; ocular ridges distinct, 

 directed anteriorly in passing from the eye to the dorsal furrow. Frontal 

 limb short, not more than one-third as long as the glabella, one-half of 

 its length formed by the strong, rounded marginal rim and furrow. 

 Facial suture directed gently inward from, the front of the eye lobe to 

 the anterior margin, with but little curvature; behind the eye it is 

 directed backward and outward at an angle of from thirty-five to forty 

 degrees with the occipital line of the head, with a slightly sigmoidal 

 curvature, giving an elongate triangular form to the postero-lateral 

 limbs. 



There is considerable variation in the form and proportions of the 

 glabella among the different individuals in the collection, the larger 

 specimens being proportionally broader and the lateral furrows much 

 more distinctly marked. On the smaller one figured the furrows are 

 not distinct enough to indicate without exaggeration. The presence or 

 absence of an occipital spine is also noticed, dependent apparently on 

 the same cause. It is possible that the two individuals may belong to 

 different species, but from their great similarity in other respects we 

 feel confident that this is not the case. 



This species resembles in some of its characters C. (Batkyurus ?) an- 

 gulatus, H. & W., from the same formation on the west side of Pogonip 

 Mountain, White Pine, Nev., described in Mr. Clarence King's report, 

 but lacks the angular frontal limb of that species, and the facial sutures 



