SALTE RASTER ASPERRIMUS. 149 



Genus SALTERASTER, Stiirtz. 



1893. Salteraster, Stiirtz, Verhandl. Naturh. Ver. preuss. Eheinl., Jahrg. 50, pp. 43, 60. 



1914. „ Schuchert, Fossilmm Catalogus, Animalia, pt. 3. pp. 7, 37, 44. 



1915. „ Schuchert, Bull. 88, U.S. Nat. Mus., pp. 173, 178. 



Generic Characters. — A Urasterellid with all its rows of adradialia exactly 

 similar. 



Stiirtz, in one of liis reviews of the Palaeozoic genera, suggested various names 

 for species which did not seem to him to belong to the genera to which they were 

 ascribed. Amongst other changes he suggested the new generic name Salteraster 

 for the species named by Salter Palaeaster asperrimus. No diagnosis of the genus 

 was given, for no very adequate description of the form had been published. 

 Nicholson and Etheridge (54, p. 320), indeed, wrote as follows: "Palaeaster asper- 

 rimus, Salter, is an unsatisfactory species. The specimens in the Museum of 

 Practical Geology have the large transverse ossicles [adambulacralia] very 

 apparent ; but as to whether there is a row inside or outside these, or both, we 

 are by no means certain. It appears, however, to have possessed only four rows 

 [that is only ambulacralia and adambulacralia alone were visible on the oral 

 surface; marginalia were not visible]." They quite rightly point out (op. cit., 

 p. 326) that this structure of the arm brings the form into close relationship with 

 their " Tetraster, sp. ind.," which is the geno-holotype of ray genus Gnemidactis 

 (p. 156). 



Schuchert (85, p. 187) in view of these remarks says : "It seems best under 

 these circumstances to refer this species to Urasterella, it being apparently near 

 U. grandis. . . . Should it prove to be generically different from Urasterella, 

 then the name Salteraster, Stiirtz, can be revived, as he names P. asperrimus as 

 the geno-holotype." I think that if Schuchert had had the specimens of P. asper- 

 rimus for examination, he would not have regarded the species as being generically 

 distinct from Urasterella, for it is certainly nearly akin to at least two species, 

 U. grandis and U. huxleyi, which he places in that genus. Personally, however, I 

 think that the characters given above warrant a generic distinction. 



1. Salteraster asperrimus (Salter). Plate XI, figs. 3, 4; Text-figs. 94 — 97. 



1857. Paheaster asperrima, Salter, Ann. Mag. Nat. Hist., ser. 2, vol. xx, p. 325, pi. ix, fig. 1. 



18G2. ,, „ Wright, Mon. British Foss. Echmoderm., Oolitic, vol. ii, pt. 1 (Pabeontogr. 



Soc. for 1861), p. 24, fig. 15 (1). 

 1866. Paheaster asperrimus, Salter, Mern. Geol. Surv. Grt. Britain, vol. iii, pp. 289, 394, pi. xxiii, 



figs. 2a, 2b, 2c. 

 1880. Tetraster (?) asperrimus, Nicholson and Etheridge, Mon. Silurian Foss. Grirvan Dist., Ayrshire, 



fasc. 3, pp. 320, 321, 326. 



20 



