ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 53
Remarks.—The genus Cord yloblastus was probably
derived from Hyperoblastus by complete closure of
the sinus areas, with consequent formation of five
spiracles and simple pores. Pentremitidea differs from
Cord yloblastus in having eight hydrospire fields that
open into spiracular slits.
CORDYLOBLASTUS ACUTANGULUS (Schultze)
75
76
Plate 23, figures 4-8; text-figs. 77-79
Pentremites acutangulus SCHULTZE, 1866, 1867, p. 225, pl. 13, fig. 6.
Description.—Calyx calcitic, oval in side view with
short conical base, lobed pentagonal in top view, 21.5
mm. long by 19.5 mm. wide, with vault 17.5 mm. long,
pelvis 4 mm. long, pelvic angle on basais 70 degrees and
on radial bodies 145 degrees, with periphery at radial lips
well above mid-height. Stem round, crenellar, 2 mm. in
diameter, with large round lumen. Basal circlet widely
conical in side view, pentagonal in basal view, 3 mm.
long by 7 mm. wide. Radials five, elongate subquadrangular
in side view, each 18.5 mm. long by 8 mm. wide,
with long narrow sinus 16 mm. long by 1.75 mm. wide.
In basal view the radial bodies each have a sharply rounded
ridge along a median line from each radial lip, giving
a strongly lobed stellate appearance to the calyx in basal
view. Radials overlap deltoids and conceal them, except
on anal side, where the hypodeltoici is visible in side view.
Deltoids four, short, not seen in side view, each with
a quadrangular deltoid body 0.5 mm. long by 0.5 mm.
wide, and deltoid lip 1 mm. wide, with a large oval spiracle
between, the deep deltoid septum connecting lip to
body. On the anal side a superdeltoid and hypodeltoid
appear to occur, with two hidden cryptodeltoids, and an
anispiracle. The hypodeltoid is pentagonal, 1.5 mm.
long by 1.5 mm. wide; it abuts against the radial limbs,
74
FIGURES 74 -76. Carpenteroblastus magnibasis (RowLEY),
Lower Mississippian, Burlington Limestone, Louisiana,
Mo. (Univ. Illinois, nos. RX22, RX194). 74. Anal
area, X15. 75. Section of aboral tip of "A" ambulacrum
(internal mold), X15. 76. Part of "A" ambulacrum,
showing main and outer side plates, X45. [Explanation.—An,
anal opening; Bf, brachiolar facet; Bp,
brachiolar pit; "C," amb.; "D," amb.; D, deltoid; ED,
epideltoid; H, hydrospire; HD, hypodeltoid; L, lancet;
0, oral opening; OSp, outer side plate; P, pore; Pf, pore
furrow; S, spiracle; Sp, main side plate.]
EXPLANATION OF PLATE 14
FIGURE PAGE
1,4,7. Conoschisma? jessieae (MILLER & GURLEY), hypotype,
3,573, Carl C. Branson coll., Univ. Missouri; Lower Mississippian,
Chouteau Limestone, Providence, Mo.; oral,
aboral, "B" ambulacral views (all X6.5) 25
2,3,5,6,8,10. Phaenoblastus caryophyllatus (DE KONINCK &
LEHON), plesiotype (figs. 2,5,8), S3,268, Springer coll.,
U.S. Natl. Mus., Lower Carboniferous limestone, Tournai,
Belgium; plesiotype (figs. 3,6,10), 19,082, Gurley coll.,
Univ. Chicago, Lower Carboniferous limestone, Tournai,
Belgium; 2,5,8, oral, aboral, "B" ambulacral views (all
X6.1); 3,6,10, oral, aboral, "D" ambulacral views (all
x6) 41
9, 11,12. Conoschisma laeviusculun2 (RowLEv), topotype,
29,904, Gurley coll., Univ. Chicago; Lower Mississippian,
Upper Burlington Limestone (chert), Louisiana, Mo.; oral,
aboral, "D" ambulacral views (all X 7 .3) 24