REVISION OF PALEOZOIC STELLEROIDEA. 249 



Sturtz proposes that the family Lapworthuridse be divided into 

 three families. In the original family will remain Squamaster, Lap- 

 worthura, HaTLaster, and Sympterura. The family Furcasteridse has 

 Furcaster, while the Palaeospondylidae embraces Palseospondylus, the 

 latter name being later changed to Palastropecten by Sturtz, as it 

 was preoccupied; the family name will, therefore, have to be 

 changed to Palastropectinidse, as was done by Bather in 1905 (p. 168). 



% Genus SQUAMASTER Ringueberg. 



Squamaster RINGUEBERG, Bull. Buffalo Soc. Nat. Sci., vol. 5, 1886, p. 5. 



Original description. "Body small. Rays long, slender, tapering, 

 flexible, and divided into annular segments. 



"Ventral side of ray with two series of paired, opposite ambulacral 

 plates, divided by a straight median line; they are irregularly sub- 

 quadrilateral, with one short side, and are arranged in pairs in each 

 series, so that two long and two short sides are joined alternately; 

 consequently there is a long transverse suture regularly alternating 

 with a short one. This disposition gives dentate lateral margins to 

 the ambulacral series. The lateral ends of the long transverse 

 sutures curve away from each other, leaving a small notch between 

 the inferior plates of each pair and the superior plates of the adjoining 

 pairs. This notch receives the inner lateral corners of the squamose 

 dorsal plates. Between the dentate elevations of the ambulacral 

 plates and the lateral margins of the dorsal plates there are large 

 triangular openings, which constituted, or in which were placed, the 

 pores. 



"Dorsal side composed of large, quadrangular, squamose plates, 

 that encircle the arm as far as the ambulacral groove of which they 

 form the margin. They are divided in the upper portion of the 

 ray by a median suture. 



"Dorsal, ray plates fimbriated on the free margins. 



"All plates are perforated by minute, closely arranged pores." 



Genoholotype and only species. 8. echinatus Ringueberg. 



SQUAMASTER ECHINATUS Ringueberg. 



Squamaster echinatus RINGUEBERG, Bull. Buffalo Soc. Nat. Sci., vol. 5, 1886, 

 p. 6, pi. 1, fig. 1. 



Original description. ' ' Body small. Rays long, slender, not widen- 

 ing at the base ; regularly tapering to a subobtuse point. Dorsal side 

 covered by thin imbricating plates, with free external margins which 

 are edged on the outer and lateral sides with closely arranged, long, 

 slender, filiform spinules, that articulate into minute rounded sockets, 

 which are scalloped out of the margin of the plate; they are slightly 

 longer than the exposed portion of the plate, and are placed about 

 their own diameter apart. 



