88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



ing around the palpebral lobe, they extend downward and slightly 

 forward a short distance and then with a broad sweep curve inward, 

 cutting the anterior margin on a line with the outer edge of the 

 palpebral lobe, Cranidium with a large glabella, concave frontal limb, 

 relatively narrow fixed cheeks, and elongate, narrow postero-lateral 

 limbs. Glabella moderately convex, with the sides gradually con- 

 verging to its broadly rounded front margin ; it is marked by four 

 pairs of short furrows that penetrate obliquely inward and backward 

 from the sides ; the two posterior lobes outlined by the oblique 

 furrows are roughly subtriangular in outline, the furrows penetrating 

 nearly one-third of the distance toward the center. The second pair 

 appears to be represented by rather prominent, slightly convex 

 tubercles, and extends about one- fourth the distance across the 

 glabella. Viewed with a transverse light, the second pair of lobes 

 appears to be a forward extension of the posterior pair of lobes, 

 since the furrows back of them are not quite so deep as the more 

 oblique furrow just inside of the inner postero-lateral margin of the 

 second pair- of furrows ; the third pair of lobes extends obliquely 

 inward and backward about one-third of the distance across the 

 glabella ; the fourth pair is outlined posteriorly by a rather deep 

 furrow that increases in width from the outer margin inward for a 

 short distance so as to form a shallow, triangular area. The anterior 

 margin of the fourth pair of glabellar lobes is just back of a pit 

 which occurs on the side of the glabella opposite the inner end of 

 the palpebral ridge. On very finely preserved specimens a narrow, 

 gently arched ridge appears to represent the extension of the palpe- 

 bral ridges on the fixed cheeks. There is also a transverse furrow 

 just within the anterior margin of the glabella. The glabellar fur- 

 rows and lobes described indicate that the glabella is formed by the 

 union of five or possibly six of the original segments of one of the 

 ancestral forms of this trilobite.' The occipital ring is separated from 

 the glabella by a furrow that is rather broad and deep on each side, 

 and narrow, shallow, and arching slightly forward across the center ; 

 occipital ring slightly convex, broad across the central portions, 

 narrowing and terminating directly in the line of the posterior inter- 

 marginal furrow of the fixed cheeks. Fixed cheeks about half as 

 wide as the glabella, nearly flat within the palpebral lobe and ridge, 

 and sloping gently down into the postero-lateral limb. They are 

 interrupted in front by the strong palpebral ridges which extend 

 backward from a point opposite the anterior pair of glabellar furrows 



'Walcott, Smithsonian Misc. Coll., Vol. 53, 1910, pp. 227-22,%. 



