102 BULLETIN 



It differs from the latter in that each axillary interbrachial plate 

 bears one stout spine, while D. eucharis has three. Further, in 

 D. eucharis six or seven of the proximal inframarginal plates of 

 each column bear on their outer side a number of small, slender 

 spines. In D. chemungensis these spines may also be present but 

 in addition each plate bears centrally a prominent tubercle for the 

 articulation of a large spine. 



Formation and locality. The type is in the Museum of Columbia 

 University, New York City (No. 6228G). It is from the Spirifer 

 disjunctus sandstone of the Chemung of " Central Pennsylvania." 



NEW GENUS. 



NEW SPECIES. 



In the University of Chicago collection there is a specimen (No. 

 14397) collected by Professor Weller in the St. Louis limestone on 

 Fountain Creek, at Waterloo, Illinois. This five-rayed asterid is 

 small, shows only the abactinal side, and has very long but narrow 

 marginals and not over six or possibly seven in a column; the basal 

 plates of adjoining columns make the axils. Otherwise the abactinal 

 skeleton of the rays consists of many small, loosely adjoining pieces 

 whose arrangement can not be made out. Nor can the disk struc- 

 ture be determined. 



The relationship of this specimen seems to be with the Promo- 

 palseasteridse, with possible nearest affinity to the genus Mesopa- 

 Ixaster. 



Measurements: R = not less than 10 mm., r = 4 mm. 



I'liODVJIOI'-A.ILi^E^STElRIlSr^B, new subfamily. 



Progressive Promopalseasteridse with the interbrachial areas com- 

 plex and composed of the single axillary interbrachials, more than 

 one pair of interbrachial marginals, and adambulacral plates. Podial 

 openings in each ambulacral furrow mainly in two columns, Jbut 

 proximally there may be two additional ones in a length never 

 more than one-third the rays. 



Contains : 



Promopalseaster, new genus. 



PROMOPAL^EASTER, new genus. 



Plates 13 to 23, 25. 

 Palxaster (part) of AUTHORS. 



Promopal&aster SCHUCHERT, Fossilium Catalogus, Animalia, pt. 3, April, 

 1914, p. 24. 



Promos, chief, and aster. The largest and chief starfishes of the 

 American Ordovic. 



Generic characters. Disk above medium size, with distinct and 

 angular interbrachial arcs. Rays five, slender to stout, more or less 

 long, and tapering. Some species attain a large growth. 



