. The Geology of Minnesota . Fig. 12.—An entire pygidium of Ptychopyge ulrichi. Cannon Falls. The lobation is clearly defined, the axis beiug relatively narrow, slightly more thanone-fifth the entire length of the shield, and extending for somewhat more thantwo-thirds the length of the pygidium, ending in a blunt, not elevated Falls. Fig. 13.—Fragment of a large pygidium of Ptychopyge ulrichi, with restoration of outline. Cannon It bears eight or nine annulations, only the first three or four being well pleurae are convex and rather short on account of the broad, concav
. The Geology of Minnesota . Fig. 12.—An entire pygidium of Ptychopyge ulrichi. Cannon Falls. The lobation is clearly defined, the axis beiug relatively narrow, slightly more thanone-fifth the entire length of the shield, and extending for somewhat more thantwo-thirds the length of the pygidium, ending in a blunt, not elevated Falls. Fig. 13.—Fragment of a large pygidium of Ptychopyge ulrichi, with restoration of outline. Cannon It bears eight or nine annulations, only the first three or four being well pleurae are convex and rather short on account of the broad, concave the articulating segment there are five ribs, with a trace of a sixth; and onthe internal cast seven or eight ribs may be discerned. Of these the first is the 710 TilE PALEONTOLOGY OF MINNESOTA. [Gerasaphes ulrlehana. bioadest; all are simple, , and all disappear quite abruptly at the marginalborder. The posterior portion of the pleurae is smooth, and the extremital area of theborder is slightly bent upward. The entire surface of the shield is covered withanastomosing, racemose, elevated lines, which are very conspicuous on the largerspecimen, and clearly apparent on the smaller. This ornament is one of the genericcharacters of the group given by Angelin: densissime striolatus. This species is notwide
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Keywords: ., bookcentury1800, bookdecade1890, bookidgeologyofmin, bookyear1897
