252 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



Aganaster gregarius we have seen and the rays are wider, and as we 

 do not know the position of the pores in the rays of Aganaster, it 

 may be our specimen does not belong to this genus." 



Remarks. — ''Seems to me to be alhed to Lapworthura, and at least 

 a member of the same family. It apparently has no ventral arm- 

 plates, but an open furrow, and thus differs \videly from Aganaster. 

 It is probably a new genus." (Gregory.) 



Formation and locality. — Not given. The specimen may be in 

 the Gurley collection of the University of Chicago. 



Genus STURTZASTER Etheridge. 



Palxocoma Salter (not D'Orbigny 1850), Rep. Brit. Assoc, 1857, Trans, of sec- 

 tions, p. 76; Ann. Mag. Nat. Hist., ser. 2, vol. 20, 1857, pp. 324, 327.— Wright, 

 Mon. British Foss. Echinod., Oolitic, vol. 2, pt. 1 (Palseontogr. Soc. for 1861), 

 1862, pp. 23, 29. — Quenstedt, Petrefactenkunde Deutsclilands, vol. 4, 1876, 

 p. 81, pi. 92, fig. 43.— Zittel, Handb. Pal., vol. 1, 1879, p. 453.— Stxjrtz, 

 N. Jahrb. fiir Min., etc., 1886, vol. 2, p. 152; Verb, naturh. Ver. preuss. Rheinl., 

 etc., vol. 50, 1893, pp. 45, 62. 



Sturtzaster Etheridge, Rec. Australian Mus., vol. 3, 1899, p. 129. — Schondorf, 

 Jabrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 1910, p. 217. 



Oenoholotype. — Palseocoma marstoni Salter. 



Remarks. — Palxocoma = Sturtzaster, Bdellacoma, and Rhopalocoma, 

 all of Salter, are very poorly known, due to the fact that the specimens, 

 though not rare, occur in a calcareous shale and are pressed flat tiU 

 they have become a thin film of plates greatly obscured by an abun- 

 dance of spines. Of P. marstoni, the genotype, the writer has seen 

 five examples, presented to the United States National Museum by 

 W. R. Billings. On the basis of the characters revealed by these 

 specimens, he was inclined to leave the genus among the Asteroidea 

 and in close association either with the Mesopalseasterinse (nearest 

 Ilesopalseaster, a phanerozonian) , or the Schuchertiidse (near Schuch- 

 ertia, a cryptozonian). 



The long, slender and serrated spines of Sturtzaster are peculiar to 

 the genus. In their abundance and character they remind one more 

 of ophiurids than of astcrids. 



The figures of Salter and Wright, if correct, recall the large-disked 

 cryptozonian genus Schuchertia, and it was this character that prob- 

 ably also led Stiirtz to refer Sturtzaster to the same group in asso- 

 ciation with the genera Palasteriscus, Loriolaster, and Clieiropteraster. 



Etheridge in 1899 called attention to the fact that D'Orbigny pro- 

 posed in 1850^ the now generic name Palxocoma for Opliiura millleri 

 Phillips of the Lias. A name once proposed can not be used again 

 in another sense, and therefore Mr. Etheridge is within the rules of 

 nomenclature in substituting for Salter's second usage of Palseocoma 



^ Prodome, vol. 1, p. 240. 



