ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 83
1 mm. wide; radials overlapping deltoids. Each plate
has growth lines subparallel to the margins except along
the adoral half of ambulacral margins of the radial limbs
where there are many aligned nodes or granules. There
are five nodes along the adoral end of each radial limb,
aligned parallel to the radiodeltoid suture, even with
adjacent side plates. Approximately 14 parallel similar
rows occur below the first, with diminishing number of
nodes, each successive row even with a successive side
plate, forming a triangular area of nodes along the ambulacral
margins of each radial limb. Radials overlap
deltoids.
Deltoids four, arrow-shaped, each 2 mm. long by 1.25
mm. wide, with exposed median septum on adorai end
of each, thus forming two spiracles in the adoral end of
each deltoid. On the anal side there appear to be two
anal deltoids—a short hexagonal epideltoid adjacent to
the oral opening and a long pentagonal hypodeltoid
aboral to the anal opening. The anal spiracles are confluent
with the anal opening, thus forming an anispiracle.
Therefore, nine openings surround the oral aperture; they
consist of eight spiracles and an anispiracle. The oral
opening is surrounded by the four deltoid lips and the
epideltoid.
Ambulacra five, each 6 mm. long by 1 mm. wide,
linear, with lancet exposed along the middle one-third of
its width near the adoral end and covered by the side
plates at the aboral end of the lancet. Side plates normally
disposed, with approximately two hydrospire pores
to each side plate between the hydrospire plate and radial
margins. Pores are absent along the deltoid margins.
There are approximately 35 side plates in a space of 10
mm. along an ambulacrum. One hydrospire fold is present
on each side of an ambulacrum.
Occurrence—Lower Mississippian, Lake Valley beds
( ?Nuni member), Lake Valley, New Mexico.
Types.—Holotype, E14,750, one small specimen described
above; paratypes, E14,750, one cut section and one
large specimen, Reimann collection (1941), Buffalo Society
of Natural Sciences, Buffalo, New York.
Genus NUCLEOCRINUS Conrad, 1842, emend.
Type-species, by original designation (monotypy).—Nucleocrintrs
elegans CONRAD, 1842.
Generic diagnosis.—Spiraculate blastoids with 11
openings around oral aperture, consisting of ten
spiracles and anus separate, five large oral plates, three
exposed anal plates or two cryptodeltoids and hypodeltoid,
with hidden superdeltoid, anal oral abutting
against cryptodeltoids, lancet covered by side plates,
an inner side plate present, one pore between side
plates along deltoid and radial margins, deltoids long,
overlapping radials, with two hydrospire folds on each
164
FIGURES 164-167. Monadoblastus granulosus FAY, n. sp.,
Lower Mississippian, Lake Valley beds, Lake Valley, N.
Mexico (Buffalo Soc. Nat. Sci., no. E14,750). 164.
Summit area, X15. 165. Basal area, X15.
166. Cross section of "A" ambulacrum, aboral view,
X 15. 167. Part of "B" ambulacrum, showing side
plates, X45. [Explanation.—An, anal opening; Bf, brachiolar
facet; Bp, brachiolar pit; C, canal (radial); D, deltoid;
ED, epideltoid; HD, hypodeltoid; HP, hydrospire plate;
L, lancet; 0, oral opening; OSp, outer side plate; P, pore;
R, radial; S, spiracle; Sp, main side plate; Z, azygous
basal.]