NO. 8 SARDINIAN CAMBRIAN GENUS OLENOPSIS 245 



The glabella is marked by three pairs of furrows that divide it into 

 two smaller anterior lobes and two posterior lobes. The two middle 

 pairs of furrows are short, transverse, and with a smooth space of 

 about one-third the width of the glabella between them ; the anterior 

 furrows have a length of about one-fourth the distance across the 

 glabella, and are not as deep as the other three pairs. The posterior 

 furrows are connected by a narrow, shallow transverse furrow. 

 Occipital furrow, narrow, distinct, and slightly curved forward. 

 Occipital ring strong, rounded, widest at the center, tapering slightly 

 toward the slight furrow separating it from the fixed cheeks. 



Fixed cheeks broad, slightly convex in compressed specimens, and 

 with a relatively large palpebral lobe situated well back toward the 

 posterior margin, as shown on the right side of fig. i. A rather 

 strong palpebral ridge extends from the palpebral lobe across each 

 fixed cheek to the dorsal furrow opposite the second glabellar lobe. 

 Free cheeks narrow within the marginal border. Visual surface of 

 eye elongate, width unknown. Facial sutures not clearly shown ; 

 they appear to cut the posterior margin well within the genal spine 

 and to curve forward to the posterior end of the palpebral lobes, 

 around which they curve and then continue obliquely forward to the 

 frontal margin which they cut on a line with a point midway between 

 the glabella and the posterior end of the palpebral lobe. 



Thorax with 19 segments. Axial lobe about one-fifth the entire 

 width, rounded, and marked on each side by a shallow, rounded 

 furrow that serves to separate the outer end of the segment as a 

 low, rounded tubercle. Pleural lobes about twice as wide as the 

 axial lobe. The lobes of each segment are formed of an inner 

 straight portion marked by a narrow furrow that starts ofif the inner 

 anterior margin and extends obliquely across the segment nearly to 

 the posterior margin at the outer body margin of the thorax, beyond 

 which slightly flattened, long, backward-curving spines add about 

 one-fifth to the width of the dorsal shield. The spinose extensions 

 of the posterior segments curve backward more and more until the 

 posterior segment almost encloses the pygidium. 



Pygidium very small, lanceolate in outline, and crossed near the 

 anterior margin by a shallow furrow. 



Surface of cephalon and body portion of thorax with a somewhat 

 irregular network of very fine, narrow ridges that give the appear- 

 ance of being a modified form of the reticulated surface so character- 

 istic of the Mesonacidae/ 



^Smithsonian Alisc. Coll., Vol. 53, No. 6, 1910, pi. 28, fig. 7; pi. 37, figs. 4 

 and s. 



