236 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



Genus STURTZURA Gregory. 



Sturtzura Gregory, Proc. Zool. Soc. London for 1896, 1897, p. 1034.— Schon- 

 DORF, Jahrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 1910, pp. 215, 237. 



fRhodostoma Sollas and Sollas, Philos. Trans. Roy. Soc. London, ser. B, voL 

 202, 1912, p. 225 (genoliolotype, Protaster leptosoma Salter.) 



" Palseophiuridge having thick, subquadrate, ambulacral ossicles 

 and narrow adambiilacral plates. The disk is fragile, and its plates 

 are small and thin: it has no marginal plates. The mouth-frames 

 are narrow and separate. 



"Distribution. — Silurian, England and Australia." 



Genoholotype. — Protaster hrisingoides Gregory. 



"RemarJcs. — This genus differs from PalseopMmn, as the ambu- 

 lacral ossicles are thick and subquadrate, instead of being in the 

 form of narrow bars; also by the absence of the strong marginal 

 plates round the disk." (Gregory.) 



Chapman in 1907 refers the genotype back to Protaster, adding: 

 "In consequence of this determination Sturtzura leptosoma may now 

 be considered as the type of the genus." This is in violation of the 

 rules of nomenclature and the generic name will stand or fall on the 

 basis of Protaster hrisingoides. 



Schondorf states: "The ambulacra of 8. hrisingoides are not 

 at all bar-shaped or subquadrate, if the figures of Chapman (1907, 

 pi. 8, fig. 2) are correct, but are also essentially boot-shaped and 

 alternate in arrangement. S. leptosoma also has alternating ambu- 

 lacra. Their identity with Lapworthura miltoni ranges them with 

 the Auluroidea, where S. hrisingoides undoubtedly also belongs. 

 That this form and with it also the genus Sturtzura is to be retained 

 as valid is very questionable, but the final answer may as well wait 

 until the originals are restudied. In any event it is plain that 

 both forms can not belong to the Lysophiurae." 



Contains the following species: 

 S. hrisingoides (Gregory). Siluric of Austraha. 

 S. leptosoma (Salter). Ludlow of England. 

 S. leptosomoides Chapman. Siluric of Australia. 



STURTZURA BRISINGOIDES (Gregory). 



Tseniaster auslralis McCoy, see Chapman 1907, p. 23 {nomen 7iudum). 



Protaster hrisingoides Gregory, Geol. Mag., dec. 3, vol. 6, 1889, pp. 24-27, fig. 1.— 



Chapman, Proc. Roy. Soc. Victoria, n. ser., vol. 19, 1907, p. 22, pi. 6, 



fig. 2; pi. y, fig. 2. 

 Sturtzura hrisingoides Gregory, Proc. Zool. Soc. London for 1896, 1897, p. 1034. 



Formation and locality. — From Siluric sandstones at Moonee Ponds 

 Creek, Flemington, near Melbourne, Australia. The type-material 

 is in the British Museum (Natural History), London. Other speci- 

 mens from the same locahty and from the parish of Yermg, Upper 

 Yarra district. Victoria, are in the National Museum at Melbourne. 



