96 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS PLACOBLASTUS ERIENSIS (Reimann) Plate 32, figures 1-3; text-fig. 202 Nucleocrinus verneuili eriensis REIMANN, 1935, p. 33, pl. 4, figs. 4-5. Description.—Calyx ellipsoidal in side view, broadly rounded pentagonal in top view, 26 mm. long by 18 mm. wide, with periphery near mid-height, and flat summit, with flat base. Basal circlet pentagonal in aboral view, 2 mm. wide, with small round stem 0.5 mm. wide in sharp central basal concavity. Each basal plate has a high round ridge extending radially from the center <strong>of</strong> each plate toward the radial lips, except on the "D' ambulacral side. The ridge on the azygous basal bifurcates into two low rounded ridges that extend to the "A" and "B" radial lips. Radials five, each 6 mm. long by 5 mm. wide, elongate pentagonal in side view, with a broad M-shaped radiodeltoid suture. Radial sinus short, 2 mm. long by 1 mm. wide. Deltoids overlap radials. Deltoids four, each broadly lenticular, 23 mm. long by 9.5 mm. wide, with smooth central triangular area flanked on either side by lenticular nodose areas, similar to that <strong>of</strong> Nucleocrinus. The adorai tips <strong>of</strong> each deltoid are notched by two elongate hemielliptical spiracles, one on each side adjacent to the ambulacra. On the anal side there are at least three anal deltoids, the two elongate lenticular cryptodeltoids, with the elongate quadrangular hypodeltoid between. On the adoral side <strong>of</strong> the anal opening one large plate occurs between the adorai ends <strong>of</strong> the cryptodeltoids, and possibly there is another plate below it. The upper plate is here interpreted to be an accessory anal oral, but it could be superdeltoid and the plate below could be part <strong>of</strong> the upper one, with a crack between, instead <strong>of</strong> a suture. There are five large oral plates covering the summit, each broadly triangular and interambulacral in position and (depending on interpretation) one accessory oral is recognized between the adorai tips <strong>of</strong> the cryptodeltoids. One hemielliptical spiracle is present in the adorai tip <strong>of</strong> each cryptodeltoid along the ambulacral margins. Thus, 11 openings surround the oral aperture, consisting <strong>of</strong> ten spiracles and a separate anal opening. Ornamentation <strong>of</strong> deltoids and anal deltoids is similar to that <strong>of</strong> Nucleocrinus. Ambulacra five, linear, each 29 mm. long by 1 -mm. wide, recurved below, with lancet covered by side plates, and 28 side plates in a space <strong>of</strong> 10 mm. along an ambula- FIGURE 202. Placoblastus eriensis (REimANN), Ludlowville Formation, Springbrook, New York (Buffalo Soc. Nat. Sci., no. E11,811); summit and anal areas, X10.6. [Explanation.—An, anal opening; CR, cryptodeltoid; D, deltoid; HD, hypodeltoid; 0, oral plate; S, spiracle; Su, superdeltoid.] crum. Side plates and pores disposed as in Nucleocrinus, with inner side plate present. Remarks.—This and other species <strong>of</strong> Placoblastus may be distinguished by shape, relative proportions <strong>of</strong> plates, and disposition <strong>of</strong> orals. EXPLANATION OF PLATE 31 FIGURE PAGE 1-9. Placoblastus obovatus (BARRis), ?topotypes, E21,115 (figs. 1-7,9), E21,113 (fig. 8), Buffalo Soc. Nat. Sci.; Middle Devonian, Thunder Bay Limestone, Partridge Point, near Alpena, Mich. 1 3. Oral, aboral, and "D" ambulacral views <strong>of</strong> uncrushed specimen ( X 1.5).-4-6. Oral, "EA" interambulacral, and aboral views <strong>of</strong> slightly crushed specimen with oral plates in place ( X 1.8).—Aboral end <strong>of</strong> "C" ambulacrum <strong>of</strong> specimen illustrated in fig. 5, showing main, outer, and inner side plates on polished surface (X31.5).-8. Cross section (polished) <strong>of</strong> another specimen showing deep bifurcation <strong>of</strong> two hydrospire folds on each side <strong>of</strong> an ambulacrum ( X 11.5).-9. Oral view <strong>of</strong> specimen shown in fig. 4, showing five large oral plates and large additional plate between adorai tips <strong>of</strong> cryptodeltoids ( X 5.4) 94
UNIVI ItS111' OF KANSAS PAI I ON1010(;!CAL CONTRIBMIONS I( IIINODITMA1 A ARM IF 3 PLATE 31 FA) . Ri AsTom Si 111)11.5