1896.] OF THE PALHOZOIC OPHIUROIDEA, 1039 
wings are thin. The adambulacral plates are triangular and each 
of them bears several spines. The pores forthe podia occur at 
the middle of the lateral margin of the ventral arm-shields. 
Distribution—Lower Devonian, Bundenbach. 
Type species.—Eoluidia decheni, Stiirtz, 1886. 
Genus 2. EospoNDYLUS, nov. gen. 
Diagnosis.—Dise circular. Ambulacral ossicles completely fused 
into vertebral ossicles, each of which, however, is traversed by a 
pore. The adambulacral ossicles are somewhat pear-shaped. The 
podial pores are at the posterior angles of the ventral arm-plates. 
Distribution.— Lower Devonian, Bundenbach. 
type species.—Hospondylus primigenia (Stirtz), 1886 [15. 
Pp. 7a). 
Genus 3. M1osponpyLvs, nov. gen. 
Diagnosis. — Disc circular. Ambulacral ossicles completely 
united ; each half of the vertebral ossicle is boot-shaped. The 
oral angles each consist of a pair of syngnaths without jaw-plate. 
The ventral arm-plates are small, and are not notched by podial 
pores. 
Distribution —Lower Devonian, Bundenbach. 
Type species— Miospondylus rhenanus (Stiirtz), 1893 (17. p. 29, 
pl. i. figs. 1-3). 
Remarks.—The two genera Hospondylus and Miospondylus are 
both founded on species described by Stiirtz, and included by him 
in Ophiura. It is impossible that they can remain in this genus, 
and Stiirtz, no doubt, only placed them there provisionally. They 
agree in family characters with Holuidia, but differ from it in the 
structure of both the ambulacral and adambulacral plates. The 
differences between them would certainly rank as of generic value 
among recent Ophiurids. To leave the two species in Holuidia 
would only encourage the neglect of specific characters and a 
looseness of description which has already greatly retarded the 
study of the fossil Ophiurids. 
Genus 4. Acanaster, Miller & Gurley, 1890. 
Syn. Ophiopege, Bohm. 
This genus was proposed by its authors to include a species 
described as Protaster gregarius by Worthen and Meek. It has 
nothing to do with Protaster and is clearly a member of the 
Streptophiure. As far as its characters are known to me it must 
be included among the Holuidide. It differs from the rest of this 
family by the presence of dorsal arm-plates. 
Without the opportunity for the examination of more specimens 
than there are in the British Museum, I do not care to attempt a 
new diagnosis. Improvements on the original diagnosis of Miller 
and Gurley must be left to American palzontologists. 
Proc. Zoou, Soc.—1896, No. LX VII. 67 
