Dimensions.—There are nine entire specimens of the dorsal shield exclusive of the free cheeks. The average length is 15 mm. The different parts have the following dimensions:
| Cephalon: | mm. | |
| Length | 6.5 | |
| Width at posterior margin | 9 | |
| Length of glabella and occipital ring | 5 | |
| Width of glabella at base | 3.5 | |
| Thorax: | ||
| Length | 7.5 | |
| Width at first segment | 8 | |
| Width at last segment | 5 | |
| Pygidium: | ||
| Length | 2 | |
| Width at anterior margin | 4.5 | |
Observations.—This species is the only one of the genus Anomocarella of which we have specimens showing the cephalon, thorax, and pygidium, with the exception of the compressed dorsal shield of Anomocarella chinensis. The cranidium differs from that of the type of the genus, A. chinensis, in having a relatively smaller palpebral lobe, and twelve segments, instead of eight, in the thorax.
Formation and locality.—Middle Cambrian: (90x) Conasauga formation; in and attached to the outer surface of siliceous nodules in argillaceous shales, Coosa Valley, east of Center, Cherokee County, Alabama.
Collected by A. M. Gibson, 1884; and Cooper Curtice, 1885.
Genus COOSIA, new genus
The description of the genotype Coosia superba and the observations accompanying it may be taken as the description and discussion of the genus.
Genotype.—Coosia superba Walcott.
COOSIA SUPERBA, new species
Plate 16, figs. 1, 1a
Dorsal shield large, elongate-elliptical in outline; axial lobe of medium width, conical, and narrowing from the cephalon gradually to the middle of the pygidium where it disappears.
Cephalon semicircular in outline, moderately convex, genal angles unknown. The facial sutures cut the posterior margin some distance within the outer margin and extend inward and forward with a slight sigmoid flexure to the base of the palpebral lobe; arching about
