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PALEONTOLOGY OF NEW YORK. 
more like those of Eumetria Verneuiliana, Hall. The hinge-plate bears two short 
processes on its posterior edge, which extend only for a short distance into the 
umbonal cavity; this organ is very imperfectly known, but as far as under¬ 
stood it seems to be nearer in structure to that of Hustedia than of Eumetria. 
Acambona prima was described from the lower beds of the Burlington 
limestone, and it is quite probably identical with the species described by 
Professor Swallow, at an earlier date, as Retzia Osagensis, from the Choteau 
limestone. 
Genus HUSTEDIA,* gen. nov. 
PLATE LI. 
1858. Tei’ehratula, Maecod. Geology of North America, p. 51, pi. vi, fig. 11. 
1859. Retzia, Meek and Haidbn. Proc. Acad. Nat. Sci. Philadelphia, vol. iii, second ser., p. 27. 
1860. Retzia, McChesney. New Palaeozoic Fossils, p. 45. 
1866. Retzia, Gbinitz. Carbon und Dyas in Nebraska, 39, pi. iii, fig. 6. 
1868. Retzia, McChesney. Trans. Chicago Acad. Sciences, vol. i, p. 32, jd. i, fig. 1. 
1872. Retzia, Meek. Hayden’s U. S. Geol. Survey Nebraska, p. 181, pi. i, fig. 13 ; pi. v, fig. 7. 
1874. Eumetria, Derby. Bull. Cornell University, vol. i, p. 4, pi. viii, figs. 4, 5, 7, 8, 10 ; pi. ix, fig. 3. 
1875. Terehratula, Marcou. Trans. St. Louis Acad. Sci., vol. iii, p. 252. 
1875. Retzia, White. Wheeler’s Geogr. Surveys West of 100th Meridian, vol. iv, pp. 141, pi. x, fig. 7. 
1883. Eumetria, Waagen. Palajontologia Indica, ser. xiii, vol. iv, p. 487. 
1884. Retzia, Walcott. Monogr. U. S. Geol. Survey, vol. viii, p. 220, j)l. vii, fig. 5. 
1884. Retzia, White. Thirteenth Ann. Rexit. State Geologist Indiana, ji. 136, jil. xxxv, figs. 10-12. 
In external characters the shells constituting this genus are indistin¬ 
guishable from those of Eumetria, except in their much coarser plication. 
For this reason they have been classed under the latter genus by several 
writers, though the internal structure in the two groups is curiously distinct. 
While the complicated structure of the interior in Eumetria was not under¬ 
stood such an association of the species was altogether natural. The type of this 
new genus the Terehratula Mormoni, Marcou (= Retzia punctulifera, Shumard),— 
a characteristic species of the upper Coal Measures in both North and South 
America. The essential difference of this species from Eumetria vera lies in the 
* To the memory of the Honorable James Willia.m Husted, this interesting and widely distributed genus 
of Brachioxiods is dedicated. A patron and jiromoter of science, who, during a jieriod of more than twenty 
years, as Reju’esentative in the Assembly of the Legislature of New York, zealously espoused the interests 
of the PaliEontology, and of every other department of the Natural History of the State of New York. 
A wise legislator and educator, a faithful and unswerving friend and counsellor of many years, his name 
deserves to be spoken with resjiect and reverence wherever geologic science shall be taught or studied, 
throughout the civilized world. 
