150 BRITISH PALEOZOIC ASTEROZOA. 



1886. Palseaster (?) asperrimus, Stiirtz, Palseontographiea, vol. xxxii, p. 91. 



1893. Salteraster asperrimus, Stiirtz, Verhandl. Naturh. Ver. jireuss. Rheinl., vol. Jahrg. 50, pp. 43, 60. 



1914. Urasterella (?) asperrima, Sehuchert, Fossilium Catalogus, Auimalia, pt. 3, pp. 37, 44. 



1915. Urasterella (?) asperrima, Sehuchert, Bull. 88, U.S. Nat. Mus , p. 187. 



Material. — Moulds of portions of three individuals are known, in the Museum 

 of Practical Geology, Jermyn Street. The holotype figured by Salter consists of 

 both mould and counterpart (7435 and 743G). The other two specimens (25335 

 and 2533G) are moulds of portions of the apical surface. The holotype is preserved 

 in rather a curious position, the arms not radiating but bunched together (PI. XI, 

 fig. 3). The specimen of U. grandis figured by Sehuchert (85, pi. xxviii, fig. 1) 

 is also preserved in this position. 



Specijic Characters. — Arms highly convex, cylindrical, long. Radialia stout. 



Apical Surface (Plate XI, figs. 3, 4 ; Text-fig. 94). — Unfortunately none of the 

 specimens are in a sufficiently good condition to allow one to make a plan of the 

 whole of the apical ossicles with any certainty. The moulds of all the specimens 



Text fig. 94. — Wash drawing of a portion of the apical surface of the arm of Salteraster asperrimus, 

 slightly diagrammatised. I.M., infero-marginalia ; i?., radialia. x 5. 



are broken, so that only a portion of the disc is preserved. One of the arms of the 

 holotype is preserved in full apical view, but the mould of this is cracked down the 

 middle. In consequence, only portions of the arm can be studied, but these allow 

 one to obtain a fairly complete idea of the arrangement of the arm-ossicles. 



Text-fig. 94 shows the arrangement of the ossicles at about the middle of the 

 arm-length. The arm is bordered by stout, almost circular, infero-marginalia, 

 each with an inner nose and a stout paxilla-shaft. The middle of the arm is 

 occupied by prominent radialia. These have a stellate base, much more circular in 

 appearance than in U. ruihveni, var. leintwardinensis and U. tUraivensis. In fact 

 they look very similar to the radialia of the American species U. grandis (85, p. 27, 

 fig. G). They follow one another in regular sequence. Between the radialia and 

 infero-marginalia there are five rows of adradialia, all of which are very similar in 

 appearance. Each adradial looks as if it were V-shaped with the point of the 

 V directed towards the margin. If a displaced ossicle be examined it is seen that 

 this is not the real shape. The base is quadrate rather than triangular, but carries 

 on it a somewhat wedge-shaped paxilla-shaft. The broadest end of the shaft is the 

 inner extremity, from which it tapers somewhat outwards. The result is that the 

 paxilla-shaft makes the whole ossicle look V-shaped in surface view. Reference 



