Mr. J. W. Salter on some new Palceosoic Star-fishes. 325 



pressed spines. Ambulacra of slender remote ossicles, bordered 

 by reticular plates, with club-shaped spines. 



Fam. Ophiurid^, 



Genus 4. Protaster, n. g. Arms elongate, extending much 

 beyond a circular, closely reticulate disk. The arms are com- 

 posed above of two rows of deeply sculptured plates, spinous at 

 the edge, and below of two rows of elongate ambulacra! ossicles, 

 bordered by a row of large spinous plates. The basal ossicles 

 of the ambulacra, bordering plates, and disk, combined to form 

 a petaloid mouth below. 



Genus 5. Palaodiscus, n. g. Arms not produced beyond the 

 large plated pentagonal disk, nor distinguishable from it above ; 

 ambulacra beneath of crowded transverse ossicles, the basal 

 joints of which are greatly enlarged, thickened, and placed in 

 vertical pairs to form the mouth. 



There is not a complete series of affinities in the above five 

 genera. We want a connecting link between Palasterina and 

 Palcsocoma ; while the thick, obtuse-armed Palmaster needs some 

 intermediate form to connect it closely with the first-named 

 genus. The most difficult to place is PalceodiscuSf which most 

 resembles Palasterina in form and in the transverse shape of 

 its ambulacral bones, but which is perhaps an extremely con- 

 densed form of Ophiuridce allied to Protaster, Possibly some 

 intermediate forms may be discovered to connect these two 

 genera. 



It is not desirable in this short sketch to give more than a 

 diagnosis of each species, as I hope more fully to describe them 

 in a Decade of the Geological Survey. 



Pal^aster, J. Hall. 



We have materials to show both the upper and under surfaces, 

 the former tuberculato-spinose, the latter with deep ambulacral 

 grooves bordered by large plates. The madreporic tubercle is 

 present in our figured species. 



1. P. asperrimus, n. sp. PL IX. fig. I. 



P. triuncialis, convexissimus, brachiis brevioribus, fere cylindricis 

 obtusis ; pagina superiori tuberculis 1 2-fariis plurimis exasperata, 

 nee coronata ; ambulacris profundis, ossiculis marginalibus acuti- 

 carinatis, trans ver sis. 



Very like Asteriscus crassus (Gray) in general form. 

 Loc. In the Caradoc or Bala sandstones, at a spot called the 

 Quakers' Burying-ground, near Welchpool, N. Wales. 



