North American index fossils, invertebrates . FlG. 1927. Encope macropkcra, lateral and dorsal views. Natural size.(After McCrady.) low, posterior lateral pair deepest; periproct on proximal slope ofposterior lunule. Related to recent E. grandis Agassiz of LowerCalifornia coast. Pliocenic marls of South Carolina. ECHINODERMA TA—ECHINOIDEA. 595 Order SPATANGOIDA EcHiNOBRissus variable, concave beneath. Ambulacra unequal, open atthe end of the subpetaloid parts. Pairs of pores in simple series,the outer ones elongate. Below the subpetaloid parts the pores arein small obli
North American index fossils, invertebrates . FlG. 1927. Encope macropkcra, lateral and dorsal views. Natural size.(After McCrady.) low, posterior lateral pair deepest; periproct on proximal slope ofposterior lunule. Related to recent E. grandis Agassiz of LowerCalifornia coast. Pliocenic marls of South Carolina. ECHINODERMA TA—ECHINOIDEA. 595 Order SPATANGOIDA EcHiNOBRissus variable, concave beneath. Ambulacra unequal, open atthe end of the subpetaloid parts. Pairs of pores in simple series,the outer ones elongate. Below the subpetaloid parts the pores arein small oblique pairs sometimes united by grooves. Peristomeanterior to center. Periproct at upper end of a groove situatedon the upper surface of the test. Fig. 1928. a-c, Echinobrissus texanus, upper, under and side views ; d-g, Cussi-dulusjlorealis, lower, lateral and upper views and enlargement of right postero-lateralambulacrum. (After Clark.) 37. E. texanus Clark. (Fig. 1928,a-c.) Cretacic. Test ovate, rounded and low anteriorly, subquadrate narrow. Apical disk forward of center. Mouth open-ing small. Austin chalk (Niobrara) of Texas. XXV. Cassidulus small, oblong, depressed convex dorsally, flat below; ambu-lacra short, subpetaloid, not closing; pores continued from themiddle part to the well-developed floscelle; mouth in front ofmiddle; periproct longitudinally elongated, on the upper posteriormargin. Cretacic-Eocenic. 596 NORTH AMERICAN INDEX FOSSILS. 38. C. florealis (Morton). (Fig. 1928, c?-^.) outline somewhat five-angled, angular posteriorly. Apex slightly in front of center. Interambulacra wide, coveredwith small perforated tubercles; peristome pentagonal, with theambulacr
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