S3 
in form ; the posterior one heptagonal, and larger than any of the rest ; that 
to the left pentagonal ; the three others hexagonal ; upper side in four of 
the plates angular, in the other truncate, supporting the right postero-lateral 
radial. Radial plates five, irregular in form and size, the postero-lateral 
considerably smaller than the others ; two posterior radials as well as the 
anterior one pentagonal, truncate above, and supporting a short snhqnad- 
rangnlar costal ; the two anterior ones hexagonal, angular above, supporting 
on each side an arm ; line of articulation between the three former radials 
and their respective costals is widely gaping, and the mode of articulation is 
similar to that of all later Poteriocrinidse ; the two other radials, which have 
angular upper faces, are slightly constricted along their upper ends so as to 
indicate an anchylosis of costals and radials. Costals, although short, are twice 
as wide at their union witli the radials as along their upper ends, Avhich are 
truncate and moderately concave, each supporting a single arm ; azygous^ 
plate is unusually large, pentagonal, placed obtusely between the posterior 
basal and right postero-lateral radial ; its upper angle, which extends almost 
to the top of the radials, is slightly truncated, and supports the first plate of 
the ventral tube, and its left nj^per side abuts against a large pentagonal anal 
plate. Column apparently small and circular. [Wachsmuth and Spritiger)? 
Ohs . — This “ singular crinoid,” as Sir P. M‘Coy aptly termed it,® or as 
Prof, de Koninck said,^ “ genre im pen anomal,” was little understood until 
the appearance of the third part of Messrs. Wachsmnth and Springer’s 
“ Revision of the Palaeocrinoidea.” 
1 Azygous, unpaired; or, parts that are apparently single, or have no symmetrical fellow. 
^ Slightly emended, R. Etheridge, junr., 1892. 
^ Ann. Mag. Nat. Hist., 1847, XX, p. 228. 
* Foss. Pal. Nouv.-Galles du Sud, 1877, Pt. 3, p. 101. 
