1896.] OF THE PAL EOZOIC OPHIUROIDEA. 1035 
form of narrow bars; also by the absence of the strong marginal 
plates round the disc. The genus contains two species, S. brisin- 
goides (Greg.) and S. leptosoma (Salt.) (13. p. 331, pl. ix. fig. 5], 
both of which were originally placed in Protaster. 
The genus differs from Protasier by the family character of 
having bar-shaped instead of boot-shaped ambulacral ossicles. 
I have pleasure in naming this genus after Herr Stiirtz, whose 
careful dissections have added so greatly to our knowledge of the 
Palzozoic Ophiurids, and who has previously pointed out [17] that 
these two species are generically distinct from Protaster. 
Genus 3. T#NIURA, nov. gen. 
Diagnosis.—Paleophiuride with a small pentagonal disc, not 
bounded by marginal ossicles. The ambulacral furrow is broad. 
The oral skeleton is conspicuous and the syngnaths each composed 
of two separate pieces. The two jaws of each oral angle are 
closely attached; the mouth-frames are separated and each of 
them is a short, thick, slightly bent bar. 
Distribution.—Trenton Limestone, Ottawa. 
Type species—Teniura cylindricus (Billings) [2. pp. 81-82, 
pl. x. figs. 4a, 46]. 
Remarks.—This genus differs from Paleophiura by the absence 
of marginal ossicles from the disc, and from Sturtzura by the 
smaller size of the disc and the form of the syngnaths. In 
Sturtzura the jaws end bluntly against a jaw-plate, whereas in 
Teniura they appear to taper to a point and have no jaw-plate. 
This genus is necessary for the second species included by 
Billings in his genus Teniaster. The genus was described as dise- 
less, which in respect to the type species S. spinosus is correct. 
In that species the oral skeleton consists of five pairs of large 
adambulacrals as in ordinary Asterids. The affinities of the true 
Teniaster appear to me to be with such forms as Falcaster 
ruthveni (Forbes) [4. dec. 1, pl. i. fig. 1]. It is asteroid in the 
oral armature, in its alternately arranged ambulacral ossicles, and 
in the absence of a disc. I therefore consider Teniaster a genus 
ot Asteroidea. The second species placed by Billings in this 
genus has, however, a well-marked disc *, and bas the oral arma- 
ture composed of five pairs of Ophiuroid syngnaths. It must 
therefore be included among the Ophuiroidea. 
Genus 4. Eveasrer, Hall, 1867 [6. p. 290, pl. ix. figs. 7, 8]. 
Diagnosis.—Paleophiuride in which the ambulacral ossicles are 
subheptagonal in form, the central suture along the arm being 
zigzag, while the outer angles of the ossicles are cut away for the 
1 Billings in his description (2, p. 81) attributes the alternation of the 
ossicles in Teniaster spinosus to distortion; but this explanation is not con- 
sistent with his figure. If distortion had separated the pairs of ambulacral 
ossicles it ought also to have displaced the syngnaths; but those of each pair 
are left precisely opposite. 
? Billings, op. cit. pl. x. fig. 4a. 
