KIRKBYIDAE 



53 



ter, placing kirkbyan pit exactly at its 

 antero-ventral edge; anterior shoulder rises 

 well above hinge line, somewhat larger than 

 central node ; posterior node much smaller, 

 barely rises above the hinge ; reticulations 

 fairly coarse especially near keels; several 

 short, thin spine-like protuberances also 

 mark surface. 



Length, 0.68 mm ; height, 0.40 mm ; 

 thickness, 0.38 mm. 



Renault formation, locality 9, common; 

 Vienna formation, locality 10, abundant. 



PoLYTYLiTES GROVEi (Croneis and Gutke) 



Amphtssites gro'vei Croneis and Gutke, 1939, Bull. 

 Denison Univ., Jour. Sci. Lab., vol. 34, pi. 2, 

 figs. 28, 29, Renault formation. 



POLYTYLITES? NODOBLIQUUS 



(Croneis and Gale) 



Plate 10, figures 38-41 



Knightina nodobliqua Croneis and Gale, 1938, 

 Bull, Denison Univ., Jour. Sci. Lab., vol. 33, 

 p. 274, pi. 5, fig. 1, Golconda formation. 



Carapace large, rectangular, with large 

 oval central node elongated along line ris- 

 ing a little toward anterior end ; terminal 

 swellings not sharply defined, rise gradually 

 to form regular ridges sharply curved 

 posteriorly to parallel the single very faint 

 carina; carina not keel-like, but broad and 

 rounded, forming a broad, flat area along 

 ventral margin ; anterior shoulder elevated 

 but little above hinge line and gradually dies 

 out on a line slightly below pit ; reticulations 

 fine to coarse, elongate on the carina. 



Length, 0.97 mm ; height, 0.50 mm ; 

 thickness, 0.58 mm. 



Renault formation, locality 12, rare; 

 Paint Creek formation, locality 24, rare; 

 Golconda formation, locality 8, common; 

 Vienna formation, locality 10, common. 



POLYTYLITES QUINCOLLINUS (Harlton) 



Plate 10, figure 45 



Maury ella quincollina Harlton, 1929, Am. Jour. 

 Sci., ser. 5, vol., 18, p. 257, pi. 1, fig. 5, 

 Fayetteville shale. 



Carapace large, rectangular in outline ; 

 coarse surface reticulations interrupted by 

 five nodes or swellings; central and antero- 

 dorsal nodes rise abruptly, others are lower 

 and rise gradually above surface; reticula- 

 tions apparently without orderly arrange- 

 ment and occur without interruptions over 



all protuberances ; inner keel almost ob- 

 literated by ventral nodes which form pro- 

 minent saddle just below central node; pit 

 deep, elliptical, with long axis 45° to hori- 

 zontal, rising toward anterior end. 



Length, 0.91 mm; height, 0.51 mm. 



Renault formation, locality 9, rare. 



This species, because of its five swellings, 

 large size, and coarse reticulations has been 

 identified as P. quincollinus (Harlton). 

 Comparative material from the lower 

 Fayetteville shows some variation in size 

 and extent of the ventral swellings. Some 

 forms also axhibit a more orderly arrange- 

 ment of reticulations than does the specimen 

 from the Renault. 



POLYTYLITES RETICULATUS Cooper, n. sp. 

 Plate 10, figure 10 



Carapace coarsely reticulate, especially in 

 area between two false keels ; first carina 

 parallel to free margin; central node rela- 

 tively small, almost round, with kirkbyan pit 

 at antero-ventral edge ; inner carina sub- 

 parallel somewhat widely separated from 

 outer one by four rows of very large, oval 

 to subangular reticulations ; anterior node 

 well developed, larger than central node, 

 projecting well above hinge line; posterior 

 node small, inclined slightly forward from 

 vertical, projecting slightly above hinge line. 



Length, 1.06 mm; height, 0.60 mm. 



Clore formation, locality 4, abudant. 



POLYTYLITES siMiLis (Croneis and Gale) 



Amphtssites similis Croneis and Gale, 1938, Bull. 

 Denison Univ., Jour. Sci. Lab., vol. 33, p. 269, 

 pi. 5, fig. 6, Golconda formation. 



POLYTYLITES SUBLINEATUS 



(Croneis and Thurman) 



Plate 11, figure 24 



Amphissites suhlineatus Croneis and Thurman, 

 1938, Bull. Denison Univ., Jour, Sci. Lab., 

 vol. 33, p. 315, pi. 8, fig. 16, Kinkaid forma- 

 tion. 



Length, 1.05 mm; height, 0.67 mm. 



Kinkaid formation, locality 5, common. 



POLYTYLITES SUPERUS (Croneis and Gale) 



Plate 11, figures 6, 17 



Amphissites siiperus Croneis and Gale, 1938, Den- 

 ison Univ. Bull., Jour. Sci. Lab,, vol. 33, 

 p, 272, pi. 5, figs, 13, 14, Golconda formation. 



