The American Midland Naturalist 
PUBLISHED BI-MONTHLY BY THE UNIVERSITY 
OF NOTRE DAME, NOTRE DAME, INDIANA 
VOL. VIII. JULY anno SEPTEMBER, 1923. NOS. 10-11 
—_——— 
Nortonechinus, a Devonian Echinoid. 
CARROLL LANE FENTON AND MILDRED ADAMS FENTON. 
Among the fossils of the Hackberry Stage of the Upper 
Devonian of Iowa there occur numerous fragmentary remains 
of echinoderms. The most common of these consist of the 
plates and spines of an echinoid, called by Mr. A. O. Thomas, 
of the University of Iowa, Nortonechinus. So far as we are 
aware, the name has been used in print enly in papers by the 
senior author,! who was under the impression that Mr. Thomas 
had described the genus, since he used the name. Since, after 
six years of waiting, no diagnosis has appeared, we publish 
the accompanying description of the fossil indicated by 
Thomas’s nomen nudum. 
Phylum ECHINODERMATA 
Class ECHINOIDEA Bronn. 
Genus NORTONECHINUS Thomas (nom. nud.) 
Genotype: Nortonechinus primus Nn. Sp. 
Description.—The general form of the genus is not deter- 
minable; probably it very closely resembled that of the modern 
Colobocentrotus, except that the outer spines are long and 
sharp instead of flattened. The spines are short and heavy 
over most of the body, with flat, polygonal outer surfaces, that 
evidently fit together so as to form a natural armor-plate. The 
flat surfaces are variously patterned, with rows of granules 
and bosses. There are variations in the spines, some of them 
1 American Journal of Science, ser. 4, vol. 48, p. 371; American Mid- 
land Naturalist, vol. 6. p. 191. 
*See Lankester’s Treatise on Zoology, part 3, Eichinoderma, by F. A. 
Bather, pp. 313-314, fig. 34. 
