NO. lO CAMBRIAN FOSSILS, 4TH CONTRIBUTION RESSER 



II 



GASTROPODA 



PALAEACMAEIDAE Grabau and Shinier 



HELCIONELLA Grabau and Shimer, 1909 



HclcioncUa Grabau and Shimer, N. A. Index Foss., vol. i, p. 607, 1909; 

 Smetana, Roz Ceske Akad., vol. zy, no. 8, p. 3, 1918. 



Grabau and Shimer erected Hclcionella on Stenothcca rugosa 

 without recognizing the fact that four species were inckided in Wal- 

 cott's figures copied by them. Many of the numerous errors of gen- 

 eric reference and specific determination are not inckided in the 

 present brief study. Confusion possibly still exists between Hclcio- 

 ncUa and Stenothcca. In fact, this and related, or similar forms, 

 should undergo detailed monographic study in the near future. 



Authors compare Hclcionella with Palaeacinaca, distinguishing the 

 former on the basis of the submarginal position and incurved shape 

 of the apex. It may be that when the interior structure of Helcionella 

 is obtained, the genus will be found to be synonymous with Pannor- 

 phorclla, which it resembles outwardly. 



Genotype: Metoptomaf rugosa Hall. 



Published species of Hclcionella are listed together with their syno- 

 nyms. New names and new species are then discussed. 



Atlantic Province 



Hclcionella annidata Smetana 



" (Callocomis) ava Smetana =; H. az'a 



" amis exccntrica Smetana = H. cxcentrica 



" cingulata Cobbold 



" comlcyensis Cobbold 



" ? cniarginata Cobbold = H. cmarginata 



" lata Smetana 



" lata glabra Cobbold 



" maxima Cobbold 



" media Cobbold 



" oblonga Cobbold 



" pompeckji Cobbold 



" cf. rugosa Kiaer =z H. kiacri 



" rtigosa acitticosta Kiaer = H . norvegica 



" tjerovicensis Smetana 



" tenuis Smetana 



North America 



Hclcionella cingulata ? Poulsen = Indeterminable fragment 



„ , ,,, , f= Stenothecoides elongata 



elongata Walcott^ ,, 1 / j • 



( ^ labradonca 



" pricei Resser and Howell 



