222 



BULLETIN 



UNITED STATES NATIONAL MUSEUM. 



Genus EOPHIURA Jaekel. 

 Text figs. 19, 20. 

 Eophiura Jaekel, Zeits. geol. Gesell., vol. 55, 1903, Protokol, p. 14 (107), figs. 1, 4. 

 GenoJiolotype. — Eophiura, species not named. To give this genus 

 proper standing according to the rules of nomenclature, the form is 

 here named E. hohemica, new species. It is the only species of the 

 genus, and occurs in the Ordovicic (D^) at Osek, Bohemia. 



The genus is not defined in the regular manner, but from the general 

 discussion and the illustrations the following has been made out: 



Rays outside of the disk, 

 apparently petaloid i n 

 form, with wide-open am- 

 bulacral furrows, having 

 narrow alternating ambu- 

 lacralia that are I — shaped, 

 with the podial openmgs 

 excavated on each side of 

 the lateral extensions. 

 The adambulacrals are 

 very large, drawn out lat- 

 erally, rectangular, lie hori- 

 zontally, and in no way 

 resemble the side plates of 

 typical ophiurids, or, for 

 that matter, even the Lys- 

 ophiurse. The lateral 

 edges of these ossicles are 

 slightly elevated, tubercu- 

 lated, and each bears about 

 four long and very slender 

 spines. Inside of the disk 

 the adambulacrals are nar- 

 row and stand vertically 

 as m Paleozoic ophiurids ; 

 the columns first diverge 

 and then converge in the mouth area. The two proximal pieces of 

 each column make the adambulacral mouth extensions, with the 

 terminal ossicles of adjacent columns side by side but not coalesced, 

 forming the sjmgnaths. The two most proximal ambulacrals rapidly 

 decrease in size, enlarging the mouth area, with none of these ossicles 

 on each side of the two final adambulacrals. 



The disk seems to be small, with concave interbrachial sides. 

 ActinaUy these areas are covered with scale ossicles. Madreporite 

 ventral, in the outer and lateral part of an interradius. Immediately 

 outside of the syngnaths occur interradially two small ossicles, 

 reminding one of vestigial mframarginalia. 



Fig. 19.— End of a bay of Eophhtba bohemica, much en- 

 larged, AFTER Jaekel. a, ambulacrall*.; ad, adambula- 

 cralia; Afg, pit of podia; ads, lateral extension of 

 adambulacralia; Rt, radlal furrow; St, spine bases. 



