NO. 3 LOOP DEVELOPMENT OF CRYPTACANTHIA—COOPER 17 
and form, paratype U.S.N.M. No. 127208z. 14, 15, Brachial views of 
two individuals more slender than normal, 3, paratypes U.S.N.M. 
Nos. 127208y and 127205s. 16-20, Anterior, posterior, side, pedicle, and 
brachial views, respectively, 3, of the holotype U.S.N.M. No. 
127066. 21, Posterior half of a large adult showing the oval foramen 
and deltidial plates, X 6, paratype U.S.N.M. No. 127205t. 
E. Cryptacanthia prolifica Cooper, new species. 
Fig. 22. Posterior part of a brachial valve showing the cardinalia with 
the convex inner plate and its foramen, <.6, paratype U.S.N.M. No. 
127205). 
F. Cryptacanthia prolifica Cooper, new species. 
Fig. 23. Imperfect loop, 6, with hood broken away to show the 
posterior extensions of the hood attachment and the jugum, paratype 
U.S.N.M. No. 127207p. 
G. Cryptacanthia prolifica Cooper, new species. 
Fig. 24. Partial side view of a small specimen, about 5 mm. long, show- 
ing small hood, spiny descending branches, and crural processes, X 6, 
paratype U.S.N.M. No. 127204s. 
H. Cryptacanthia compacta White and St. John. 
Fig. 25. Side view of a lump of calcite containing a complete loop, X Io, 
showing the small erect hood, hypotype U.S.N.M. No. 9382a. Speci- 
men from Pennsylvanian, Madison County, Iowa. Photograph taken 
under water. Note long spines in lower left. 
I. Cryptacanthia prolifica Cooper, new species. 
Figs. 26, 27. Posterior and ventral views, respectively, of a perfect loop 
showing the anterior notch in the hood, anterior cleft, and the crural 
processes, ca. X 10, paratype U.S.N.M. No. 127204t. (For additional 
views see pl. 2, G, figs. 13, 14.) 
PLATE 2 
All figures of Cryptacanthia prolifica Cooper, new species, and all from 
Grapevine Canyon locality. 
A. Stage 1.6-2.0 mm. (precentronelliform stage?). 
Fig. 1. Early loop stage showing very slender and delicate loop, ca. X 15, 
paratype U.S.N.M. No. 127202k. 
B. Stages 2.1-2.5 mm. (centronelliform stage). 
Fig. 2. Specimen showing stouter descending branches than the pre- 
ceding which unite to form an echmidium, X 8, paratype U.S.N.M. 
No. 127206r. 
Fig. 3. Another brachial valve with well-preserved loop showing long, 
pointed echmidium, X 10, paratype U.S.N.M. No. 127202s. 
C. Stages 2.6-3.0 mm. (centronelliform stage or possibly early cryptacanthiform 
stage). 
Fig. 4. Brachial valve showing loop with echmidium and incipient bud 
(?) of the hood, X 10, paratype U.S.N.M. No. 127202u. 
Fig. 5. The loop of another specimen, 20, showing the elbow in the 
descending lamellae and the echmidium with a thickening, possibly 
the bud of the hood, paratype U.S.N.M. No. 127202w. 
