REVISION OF PALEOZOIC STELLEROIDEA. 



95 



FIG. 8. SPANIASTER LATISCUTATUS, AFTER 

 SCHONDORF. SCHEMATIC ARRANGEMENT OF 

 THE ABACTINAL PLATES. C, PRESUMABLE 

 POSITION OF ANUS; Ce, CENTRAL PLATE; 

 Jn, BASAL INTERRADIALIA; mdp, PROBABLE 

 POSITION OF MADREPORITE; mo, SUPRAMAR- 

 GINALIA; RI, BASAL RADIALIA. 



thickened in the center and greatly depressed to the sutures . Thus each 

 plate has a cushioned surface. Between the ends of each plate of the 

 middle row are two minute accessory plates lying in the angles at 

 which the lateral plates enter. At the base of each ray and upon the 

 disk is a single large plate whose surface rises into a high clavate node. 

 Between each two of these is one of 

 less height.. The central portion of 

 the aboral area is destroyed and no 

 trace of madrepore is seen. 



"The width of this specimen from 

 tip to tip is 33 mm. 



"Occurrence: Jennings formation, 

 Chemung member. Yellow sandstone 

 on the road northeast of Oakland, 

 Garrett County [Maryland], where it 

 is associated with Spirifer disjunctus. 



"Collection: Maryland Geological 

 Survey." 



Remarks. This clearly determined 

 species is a late survival of early 

 Paleozoic primitive asterids. The 

 characters so far as determinable in 

 the natural mold are those of Meso- 

 palseaster, but as the disk skeleton is not preserved, it is very prob- 

 able that when this feature is known the form will be seen to belong 

 to a new genus. 



Genus SPANIASTER Sehondorf. 



Plate 12, figs. 1, 2; text fig. 8. 

 Calaster SANDBERGER (not Agassiz 1835), Verst. d. rheinischen Schicht. Nassau, 



1855, p. 381. 



Spaniaster SCHONDORF, Jahrb. nassauisch. Ver. Naturk., Wiesbaden, vol. 60, 

 1907, p. 176; vol. 62, 1909, p. 30; Palaeontographica, vol. 56, 1909, pp. 73, 109. 



Remarks. This genus with its single very small species has its 

 nearest relations with Mesopalseaster, in that it has a single axillary 

 interbrachial plate in each actinal axillary area, but differs from it 

 in that there are many more adambulacral and ambulacral plates 

 than there are inframarginals. The marked and generic difference, 

 however, is on the abactinal side, where there are but three columns 

 of plates, one radial and two suuramarginal, of large and thick ossicles 

 arranged in parallel rows, the pieces of which do not alternate with 

 one another; further, the supramarginals are almost completely 

 superposed upon the inframarginals, the two columns together, but 

 more particularly the inframarginals, bounding the rays and not the 

 inframarginals alone, and not so pronouncedly as in Mesopalseaster. 

 The disk is also more primitive in its construction, in that the central 



50601 Bull. 8815 7 



