128 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



their extreme outer edges and immediately inside of the adambu- 

 lacral plates. 



Formation and locality. — In the Richmond formation, near Waynes- 

 ville, in Montgomery County, Ohio. The holotype is in the Harris 

 collection of the United States National Museum. 



Remarks.— ■'Y\\\s, species has a general resemblance to some of the 

 Promopalseasters, particularly P. hellulus and P. wyJcoffi, but the 

 pecuUar arrangement of the axillary and int«rbrachial adambulacral 

 plates will distinguish it not only from them but from all other 

 Ordovicic asterids. 



Cat. No. 40880, U.S.N.M. 



Family XENASTERID^ Schondorf . 



Xenasteridx Gregory, Geol. Mag., dec. 4, vol. 6, 1899, p. 346; Treat. Zool., vol. 3, 



Echinoderma, 1900, p. 250. 

 Palsegoniasteridse Sturtz, Palseontographica, vol. 3G, 1890, p. 247 (not opp. 246). 

 Xenasteridx Schondorf, Palseontographica, vol. 56, 1909, p. 105; Jahrb. nassau- 



isch. Ver.Naturk., Wiesbaden, vol. 62, 1909, p. 25; vol. 63, 1910, pp. 244, 250. 



Progressive Phanerozonia having the general characters of the 

 Promopalaeasterinse, with the addition of accessory interbrachials. 

 The ambulacral and adambulacral plates are directly opposite one 

 another and do not waver between the slightly alternate and opposite 

 arrangement in the Promopalaeasterinse. Podial openings in two 

 columns in each ambulacral furrow, the apertures lying between 

 each four adjoining plates, that is, between two adambulacrals and 

 two ambulacrals. 



Contains: 



Xenaster Simonovitsch. 

 Agalmaster Schondorf. 

 Rlienaster Schondorf. 

 Eifelaster Schondorf, 

 Trimeraster Schondorf. 



Schondorf defines the family as follows (leaving out much of his 

 detail) : 



Lower Devonic starfishes with well-developed supramarginals and 

 usually still larger inframarginals ; the latter are somewhat more numer- 

 ous than the former, causing them to be unequally superposed. Ambu- 

 lacra opposite one another and opposite the adambulacrals; podial 

 openings in two rows. Actinally each interradius has either three or 

 five interbrachial plates; abactinally this area is filled with small 

 accessory plates and margined only by inframarginals. Disk skeleton 

 consisting of small separated pieces, a central disk plate, five primary 

 radiaUa, five primary interradialia, and more or less of accessory disk 



