NO. 3 CASSIDULOID ECHINOIDS — KIER I93 



Genus PLIOLAMPAS Pomel 



Pliolavipas Pomel, 1888. Bull. Soc. Geol. France, ser. 3, vol. 16, p. 446. Tj'pe 

 species by monotypy (Pomel, 1883, p. 63, pro Plesiolatnpas Pomel non Duncan 

 and Sladen, 1882), Echinolampas gauthieri Cotteau. 



Synonyms: Breynella Gregory; Milletia Duncan. 



GENERIC DESCRIPTION 



Medium size, elongate, moderately inflated; apical system mono- 

 basal with three or four genital pores, pore may be absent in left 

 anterior genital ; petals well developed, open, broad, equal, with broad 

 poriferous zones, conjugate pores, ambulacral plates beyond petals 

 single pored; periproct inframarginal ; peristome anterior, higher 

 than wide, pentagonal; bourrelets well developed; phyllodes broad, 

 with large single pores, few in inner series ; tubercles slightly larger 

 adorally, no naked granular zone adorally in interambulacrum 5. 



Comparison with other genera. — Pliolampas is distinguished from 

 Termieria in having a pentagonal peristome, more crowded phyllodes, 

 and a longer petal III. These differences may only reflect the imma- 

 turity of all the specimens known of the type species of Termieria, 

 and the two genera may be synonymous. Pliolampas differs from 

 Studeria in having an inframarginal periproct and less developed 

 bourrelets. 



Remarks. — There has been considerable confusion and controversy 

 over the number of genital pores in this and related genera. Accord- 

 ing to Lambert (1913, p. 131) there are only three genital pores in 

 the type specimen of the type species of this genus, Pliolampas 

 gauthieri. I have studied this specimen and am uncertain whether 

 there are three or four. The apical area is not well preserved. How- 

 ever, in Pliolampas pioti Gauthier there are three or four genital 

 pores. Of the seven specimens of this species in the De Loriol Col- 

 lection at Geneva, five of them have the apical system preserved. In 

 all five of these there are only three genital pores, no pore being in 

 the left anterior genital (pi. 36, fig. 5). Both Gauthier {in Fourtau, 

 1899, P- 7^Z) ^^^ Fourtau (1920, p. 62) report specimens of this 

 species with three or four genital pores. Mortensen (1948, p. 249) 

 admits that "it seems thus incontestable that in this species the num- 

 ber of the genital pores is either four or three." Regardless of this, 

 Mortensen suggests that species with four genital pores should not 

 be placed in Pliolampas, but should form a genus of their own. Such 

 an action is unreasonable, as Pliolampas pioti with both three and 

 four genital pores would have to be referred to two genera. There 



