254 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



STtJRTZASTER (?) MITCHELLI Etheridge, jr. 

 Sturtzaster (?) mitchelli ETHERIDGE, jr., Rec. Australian Mus., vol. 3, 1899, p. 128. 



Formation and locality. A single specimen from the Upper Trilo- 

 bite bed of the Siluric (Wenlock series) at Bowning, New South 



Wales. 



Genus BDELLACOMA Salter. 



Palseocoma (Bdellacoma) SALTER, Ann. Mag. Nat. Hist., ser. 2, vol. 20, 1857, p. 



324. WRIGHT, Mon. British Foss. Echinod., Oolitic, vol. 2, pt. 1 (Palee- 



ontogr. Soc. for 1861), 1862, p. 31. ZITTEL, Handb. Pal., vol. 1, 1879, p. 



453. STURTZ, Palseontographica, vol. 32, 1886, p. 96. 

 Bdellacoma STURTZ, Verb, naturh. Ver. preuss. Rheinl., etc., vol. 50, 1893, pp. 46, 



63. 



Genoholotype and only species. P. (B.) vermiformis Salter. Lower 

 Ludlow, Leintwardine, England. 



Remarks. Until this form is restudied and brought up to date the 

 supposed subgenus of Paldeocoma has no value. 



Genus RHOPALOCOMA Salter. 



Palseocoma (Rhopalocoma} SALTER, Ann. Mag. Nat. Hist., ser. 2, vol. 20, 1857, 

 p. 329. WRIGHT, Mon. British Foss. Echinod., Oolitic, vol. 2, pt. 1 (Palae- 

 ontogr. Soc. for 1861), 1862, p. 31. ZITTEL, Handb. Pal., vol. 1, 1879, p. 453. 

 STURTZ, Palaeontographica, vol. 32, 1886, p. 96. 



Rhopalocoma STURTZ, Verh. naturh. Ver. preuss. Rheinl., etc., vol. 50, 1893, 

 pp. 46, 63. 



GenoJiolotype and only species. P. (R.) pyrotechnica Salter. Lower 

 Ludlow, Leintwardine, England. 



Remarks. This form also requires modernization, and until then 

 the supposed subgenus has no value. 



Genus HALLASTER Sturtz. 



Protaster HALL (not Forbes), Nat. Hist. N. Y., Pal., vol. 3, 1861, p. 134; 



Twentieth Rep. N. Y. State Cab. Nat. Hist., 1868, p. 293; rev. ed., 1868= 



1870, p. 336. 

 Hallaster STURTZ, N. Jahrb. fur Min., etc., 1886, vol. 2, p. 150. 



Original description (Sturtz). "Ambulacral plates alternating 

 [they are opposite]; the podial pores lie between these and the side 

 plates. The dorsal skeleton consists of two columns of dorsal plates 

 and two of lateral plates, of which the former adjoin medially along 

 the rays. For P. forbesi Hall of the Silurian of North America I 

 propose the generic name Hallaster, because on the one hand Forbes 

 did not sufficiently characterize his Protaster, and on the other the 

 above species in the sense of Salter's Protaster is not congeneric 

 with it." 



GenoJiolotype and only species. Protaster forbesi Hall. 



Remarks. This genus appears to be most closely related to Lap- 

 worihura, with the most obvious difference in the shape of the am- 



