KIRKBYIDAE 



51 



Length, 0.89 mm ; height, 0.46 mm ; 

 thickness, 0.40 mm. 



Paint Creek formation, locality 24, rare ; 

 Golconda formation, locality 8, common. 



EcTODEMiTES PRIMUS Cooper, n. sp. 

 Plate 9, figures 46-47 



Carapace large, elliptical in dorsal view, 

 central and anterior swellings merged to 

 form greatly inflated antero-dorsal quad- 

 rant; enlarged portion begins just back of 

 and above pit, continues upward to above 

 hinge line and foward to inner carina; 

 carinae somewhat low, smooth, diverging 

 anteriorly; reticulations medium-sized, 

 hexagonal for the most part, fairly regular 

 especially between the carina. 



Length, 0.84 mm; height, 0.49 mm; 

 thickness, 0.53 mm. 



Kinkaid formation, locality 5, common. 



ECTODEMITES QUADRATUS Cooper, n. sp. 

 Plate 10, figures 11-12 



Carapace tumid, quadrate in lateral out- 

 line, dorsum and venter straight, parallel; 

 ends rounded ; pit elongate, almost hori- 

 zontal, subcentral ; keels low, indistinct, 

 inner one only being continuous around 

 entire free margin ; posterior end truncate ; 

 surface irregularly marked with polygonal 

 reticulations, irregular in size and shape, 

 smallest in center, becoming larger and 

 more irregular in shape toward ends and 

 venter ; greatest length and thickness central. 



Length, 0.80 mm ; height, 0.46 mm ; 

 thickness, 0.49 mm. 



Paint Creek formation, locality 21, depth 

 1304-43 feet, rare. 



E. quadradus may be distinguished from 

 E. planus n. sp. by its irregular reticulate 

 pattern, greater thickness, and lower form 

 ratio. 



EcTODEMiTES TUMiDUS Cooper, n. sp. 

 Plate 10, figures 1-3 



Carapace short, thick, widest on anterior 

 end due to prominence of well-developed 

 shoulder; central swelling rising gradually 

 from cardinal area, ending abruptly just 

 above median pit; outer carina parallel to 



II free margin, inner one becoming more 

 widely separated from first toward anterior 



i end ; reticulations subcircular to polygonal. 



Length, 0.60 mm; height, 0.33 mm; 

 thickness, 0.37 mm. 



Clore formation, locality 26, common; 

 Kinkaid formation, locality 3, rare. 



This species somewhat resembles Am- 

 phissites due to the prominence of the cen- 

 tral swelling; however, this feature is not 

 well defined except on the ventral side near 

 the pit. 



EcTODEMiTES WAREi (Morey) 



Plate 10, figure 22 



Amphissites ivarei Morey, 1935, Jour, Paleontol- 

 ogy, vol. 9, p. 477, pi. 54, fig. 7, Amsden 

 formation. 



Length, 0.63 mm; height, 0.38 mm. 



Clore formation, locality 26, common; 

 Kinkaid formation, locality 5, common. 



Genus Polytylites Cooper, n. gen. 



Amphissites, In part, of authors. 

 Mauryella Harlton, 1929, Am. Jour. Sci., sen 5, 

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



Kirkbyidae with small to large, circular 

 to ovate central node, with low to pro- 

 minent, short to elongate shoulders or 

 swellings in dorsal extermities. When the 

 latter are short and prominent the carapace 

 has a trinodal appearance. A few species 

 have swellings at the ventral extremities, 

 producing a form with a five-noded ap- 

 pearance, as in Polytylites quincollinus 

 ( Harlton) . Surface marked by kirkbyan pit 

 below central node and fine to coarse re- 

 ticulations; one to two carina more or less 

 parallel to free margin. 



Genotype. — Polytylites geniculatus n. sp. 



Polytylites ambitus Cooper, n. sp. 

 Plate 10, figure 46 



Carapace large, subrectangular, with very 

 prominent flange-like inner carina, outer 

 one poorly or not at all developed ; central 

 node large, circular, well above and behind 

 center of shell ; anterior shoulder large, pro- 

 jecting well above hinge, located some dis- 

 tance from anterior margin ; pit large, deep, 

 situated on antero-ventral margin of cen- 

 tral node ; surface finely reticulate. 



Length, 0.89 mm ; height, 0.53 mm. 



Renault formation, locality 12, rare. 



