248 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



the plates. The pores are large and situated between the contract- 

 ing sides of the ambulacral plates, the concave sides of the adam- 

 bulacrals, and the attaching ends of the succeeding plates, so that 

 they are bounded by four plates while nearly surrounded by two. 



"The oral plates form, in pairs, elongated triangles, with the 

 acute angle directed toward the center of the visceral cavity. The 

 apices are joined by a suture with the basal portions, which are 

 partly separated by a dividing furrow. A single genital pore per- 

 forates each basal section of the oral plates. Dorsal side unknown. 



"Locality and position: Prairie du Long Creek, Monroe County 

 [Illinois], Chester limestone. 



"No. 2479, Illinois State collection of 1878." 



.' TREMATASTER (?) DECHENI (Dewalque). 



Protaster decheni DEWALQUE, Ann. Soc. ge"ol. Belgique, vol. 8, 1880, pp. 52-54, 



pi. 3, figs. 1, 2. 

 Tremataster (?) decheni GREGORY, Proc. Zool. Soc. London for 1896, 1897, p. 1037, 



footnote. 



Formation and locality. Upper Devonic at Walcourt (Namur) 

 and Tohogne (Luxemburg), Belgium. 



Family LAPWORTHUKID^E Gregory. 



Lapworthuridse GREGORY, Proc. Zool. Soc. London for 1896, 1897, p. 1037. 

 STURTZ, Verb, naturh. Ver. preuss. RheinL, etc., vol. 56, 1900, p. 203. 

 GREGORY, Treat. Zool., vol. 3, Echinoderma, 1900, p. 275. SCHONDORF, 

 Palseontographica, vol. 57, 1910, p. 58; Jahrb. nassauisch. Ver. Naturk., 

 Wiesbaden, vol. 63, 1910, pp. 235, 239. 



Furcasteridx STURTZ, Verb, naturh. Ver. preuss. RheinL, etc., vol. 56, 1900, p. 

 203. SCHONDORF, Jahrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 1910, 

 p. 235. 



Palxospondylidsd STURTZ, Verh. naturh. Ver. preuss. Rheinl., etc., vol. 56, 1900, 

 p. 201. SCHONDORP, Jahrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 

 1910, p. 235. 



Original diagnosis. "Streptophiuroida without ventral armplates 

 or buccal shields; ambulacral ossicles fused, but their articulating 

 surfaces are plain. Madreporite dorsal." Schondorf states that this 

 plate is on the ventral side, and that the ambulacrals are not fused 

 (p. 239). 

 Contains the genera: 



Squamaster Ringueberg. 



Lapworihura Gregory. 



Sturtzaster Etherrdge. 



Bdellacoma Salter. 



RTiopalocoma Salter. 



Hallaster Stiirtz. 



Sympterura Bather. 



Fur caster Stiirtz. 



Palastropecten Sttirtz. 



