176 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



posed by me a little earlier, but probably published after that of McCoy; 

 and has given the two species of Urasterella to that genus. Now 

 that there seems no reason for continuing them under that generic 

 term, they should be restored to their proper position as indicated 

 above. The two species of Forbes must either be placed under 

 Urasterella as proposed by McCoy, or fall under the later genus 

 Stenaster of Billings. Were the latter genus of my own proposing 

 I should nevertheless return to Urasterella, and I have no doubt 

 that Mr. Billings will accord with this view." 



Palseaster pulcJiellus is a true Urasterella, but this does not make 

 the genus Stenaster a synonym of Urasterella, since S. salteri Billings 

 has quite another structure and is here accepted as the genotype of 

 Stenaster. 



Meek 1 also recognizes McCoy's name, but because of certain pecul- 

 iarities in S. salteri, which he recognizes as the genotype, and also 

 since he had not seen the dorsal side of McCoy's S. grandis, he prefers 

 to retain Stenaster for the latter. 



McCoy returned to his genus in 1874, after going to Australia, and 

 described a new form, U. selwyni. It is important to quote here 

 his remarks : 



" Genus Urasterella (McCoy )= Stenaster (Billings). 



"Gen. Char.: Small starfishes, with five moderate rays, narrowed 

 at the base, and without disk. Ambulacral grooves narrow, bor- 

 dered on the under side, with only one row of large (adambulacral) 

 plates; no marginal plates. Upper surface with numerous rows of 

 small tubercular plates. Confined to Silurian rocks. 



"The late Mr. Salter and Mr. Billings refer the starfishes of this 

 type to the subsequently published genus Pateaster of Hall; but, 

 as Prof. Hall objects that his genus Palseaster has ambulacral, adam- 

 bulacral, and marginal plates, and the types of my genus U. ruthveni 

 and U. Jiirudo of the English Ludlow rock, like our Australian species 

 and the American Pals&aster or Stenaster pulchella, have only one row 

 of plates on each side of the ambulacral groove, I return to the use 

 of my old generic name." 



Zittel 2 says that Stenaster is a synonym for Urasterella and defines 

 the latter genus. Stiirtz 3 points out the errors in the diagnosis of 

 Billings and that of Zittel, redefines the genus, and correctly states 

 that Stenaster Billings contains species of two genera, that is, Sten- 

 aster salteri, the genotype of Stenaster, and S. pulchella, which he refers 

 to Urasterella. In this way the genus Urasterella has come to be 

 recognized. 



The figure and description of Uraster ruthveni given by Forbes* 

 appears to be of a species generically identical with the American 



1 Pal. Ohio, vol. 1, 1873, p. 67. s Palseontographica, vol. 36, 1890, p. 219. 



2 Handb. Pal., vol. 1, 1879, p. 453. * British Org. Rem., dec. 1, 1849, p. 1, pi. 1, fig. 1 . 



