222 



BULLETIN 88, UNITED STATES NATIONAL MUSEUM, 



Genus EOPHIURA Jaekel. 



Text figs. 19, 20. 



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



GenoJwlotype. EopMura, species not named. To give this genus 



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



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



genus, and occurs in the Ordovicic (Dj) 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: 



Kays outside of the disk, 

 apparently petaloid i n 

 form, with wide-open am- 

 bulacral furrows, having 

 narrow alternating ambu- 

 lacralia that are \ shaped, 

 with the podial openings 

 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 in Paleozoic ophiurids ; 

 the columns first diverge 

 The two proximal pieces of 

 mouth extensions, with the 



FIG. 19. END OF A KAY OF EOPHIUKA BOHEMICA, MUCH EN- 

 LARGED, AFTER JAEKEL. a, AMBULACRALIA; ad, ADAMBULA- 

 CRALIA; Afg, PIT OF PODIA; ads, LATERAL EXTENSION OF 

 AD AMBULACRALIA; Rr, RADIAL FURROW; St, SPINE BASES. 



and then converge in the mouth area. 



each column make the adambulacral 



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



forming the syngnaths. 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. 

 Actinally 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 inframarginalia. 



