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ARTHROPODA 



subbnmch BRANCHIATA 



Class CRUSTACEA 



subcinss TRILOBITA 



Order OPISTHOPARIA 

 Kainily PROETIDAB 



Genus PROETUS Steininger 

 I'uoiiTus PACHYDERMATUS Barrett 



Plate LXXXIX, Fig. 1 



Proctus pacliydermatus Weller, 1903, Pal. N. J., vol. iii, p. 248, pi. xxii, figs. 

 16-21. 



Description. — " Head semicircular in outline, with a broad, flattened, 

 marginal border, the genal angles produced into sharp spines. Glabella 

 subtriangular, with a pair of small, disconnected, ovoid basal lobes, ob- 

 tusely pointed in front, bordered by a sharply defined dorsal furrow ; the 

 first and second pairs of lateral furrows are rather faint, slightly curved 

 and directed obliquely backward from the margin of the glabella ; the 

 third pair more prominent, curved, directed backward and connecting with 

 the occipital furrow by a less sharply defined depression. Cheeks convex 

 to the marginal border, the eyes opposite the third pair of lateral glabellar 

 furrows. Facial sutures making a sigmoidal curve from the anterior 

 margin of the head to the front of the eye-lobe, and after passing around 

 the eye, bending outward and cutting the posterior margin near the base 

 of the genal spines. Occipital segment broadened in the middle with a 

 small median tubercle. Thorax unknown. Pygidium semielliptical in 

 outline, broader than long, with a broad, flattened, marginal border; the 

 axis much elevated, occupying about one-third the entire width in front, 

 tapering gradually to the obtusely rounded extremity which lies just 

 within the flattened border, divided into thirteen or fourteen segments; 

 the pleurae strongly convex to the flattened border, divided into eight or 

 nine sharply grooved segments, which become obsolete at the marginal 

 border. 



