146 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 

 DIKELOCEPHALUS OSCEOLA ( n. s.). 



PLATE X, FIG. 18; AND PLATE VII, PIG. 49? 



Head small in the specimens observed, having a length of less 

 than half an inch. 



Glabella with the sides nearly parallel, slightly narrowing an- 

 teriorly, truncate in front. Occipital furrow narrow and well 

 defined : occipital ring of the same convexity as the glabella, 

 and of equal widtli throughout. Posterior glabellar furrow 

 sharply defined in the cast, and extending in a backward curve 

 entirely across and terminating a little in advance of the centres 

 of the palpebral lobe : the second furrow slightly marked on 

 the sides of the glabella. Dorsal furrow narrow and well defined 

 in the posterior part, slightly marked in front. 



Fixed cheeks narrow, expanding towards the eye : palpebral lobe 

 limited by a distinct groove, which, in its posterior inward 

 curve, extends to a point opposite the extremity of the occipital 

 ring. Frontal limb of moderate width, extended in :^"ont of the 

 glabella in a broad depression, Avhich is nearly flat in the bot- 

 tom, and thence rising abruptly in a narrow marginal rim. 



This species has been observed in three imperfect specimens of the head. 

 It resembles in general features specimens of the three preceding species 

 (D. pepinensis, D. spiniger and D. inisa); but is distinguished from all of 

 them by the wide depression in front of the glabella, and the abruptly 

 elevated narrow border. These specimens have the characteristics of the 

 Genus Dikelocephalus, as shown in all the preceding species. It occurs 

 in the sandstone at Osceola mills, associated with Ill^nurus. 



A small glabella associated with this one does not show the second pair 

 of furrows : it is more sharply truncate, and a little wider in front ; the 

 frontal limb is shorter ; the depression anterior to the glabella is narrower, 

 and the marginal rim a little stronger and very straight in front. This 

 specimen and the others are associated with a pygidium described below. 



A Pygidium (of this species?, Plate vii, f. 49) has the axis com- 

 paratively narrow and abruptly elevated, marked by six annula- 

 tions besides the anterior articulating segment. The lateral lobes 

 are marked by about four ribs, besides the anterior segment. 



The anterior margin of the pygidium is extremely curved, and 

 the antero-lateral angles are produced into long curving spines 

 which are as long as the body of the pygidium. The posterior 

 margin between the spines is rounded, and the ribs terminate in 

 a continuous thickened border. 



At least five individuals of this peculiar species have been seen. The figure is twice enlarged, 

 from a cast made in the natural mould in sandslone, associated with the glabellse described above. 



