XO. 3 CASSIDULOID ECHINOIDS — KIER 1 29 



filled with matrix giving the impression that it %vas part of the 

 periproct. In many of the specimens of ^. lamhcrti I studied, the 

 periproct appeared to be flask shaped for the same reason. 



Genus PYGIDIOLAMPAS Clark 



Pygidiolavipas Clark, 1923. Bull. Mus. Comp. Zool., vol. 63, p. 343. Type 

 species by original designation, Pygidiolampas curynota Clark. 



GENERIC DESCRIPTIOX 



Medium length, broad, circular except for pointed posterior margin, 

 adapical surface inflated, adoral flat or slightly depressed ; apical 

 system tetrabasal; petals broad, equal, closed, with very wide inter- 

 poriferous zones, tapering distally, pores conjugate, outer pore slit- 

 like, ambulacral plates beyond petals single pored; periproct infra- 

 marginal, ven.- small, longitudinal; peristome central, pentagonal; 

 bourrelets strongly developed, toothhke ; phyllodes single pored, 

 greatly broadened, with pores arranged in two series : outer series in 

 arc with approximately lo pores in each series, inner series with few 

 pores, all pores widely separated from peristome ; buccal pores present. 



Comparison zvith other genera. — This genus is very similar to 

 Hardoiiinia. Both genera have broad, equal closed petals, high, circu- 

 lar tests, and both have strikingly similar floscelles with strongly 

 developed, toothlike bourrelets and broad phyllodes with the pores 

 arranged in archke fashion around the peristome. The genera are 

 distinguished from each other by the location of the periproct. In 

 Hardoiwna the periproct is supramarginal, whereas in Pygidiolavipas 

 it is inframarginal. 



Lambert and Thiery (1925, p. 587) considered Pygidiolampas a 

 synon}Tn of Pygurus (their Echinopygus). However, they did not 

 see any specimens of Pygidiolampas, but based their decision on 

 Clark's inadequate illustrations. Pygidiolampas is quite distinct from 

 Pygurus as shown by the great diflference in their phyllodes. The 

 phyllodes in Pygurus are double pored and the pores are not arranged 

 in arcs as in Pygidiolampas, and there are no buccal pores, whereas 

 they are present in Pygidiolampas. Clark considered his genus similar 

 to Echinolampas, but in the petals in Echinolampas the outer pore of 

 a pore pair is not slitlike as in Pygidiolampas, the petals are never 

 as wide, the phyllodes do not have their pores arranged in arcs, and 

 the bourrelets are never toothlike. 



Remarks. — Morton's (1834) Clypeaster geometricus was referred 

 by Cooke (1953, p. 14) to Pygurostoma and later (1955. P- 9^) 



