CLASSIFICATION CAMBRIAN BRACHIOPODA — WALCOTT 165 



Huenella abnormis (Walcott) [1905, p. 289] : 



Fig. 9. Horizontal thin-section enlarged fifty diameters. The pores in 

 this genus are smaller than in Syntrophia, but their arrange- 

 ment is essentially the same and shows the line effect char- 

 acteristic of the Pentameracea. Upper Cambrian, Gallatin Val- 

 ley, Montana. 



Obolella crassa (Hall) [1847, p. 290] : 



Fig. 10. Horizontal thin-section enlarged fifty diameters. This shows the 

 fine granular ground-mass, with an indication in the upper left 

 side of the section that a surface ornamentation has been cut 

 across. Lower Cambrian, Bic, Canada. 



Oholus apolUnis Eichwald [1829, p. 274] : 



Figs, ii and 12. Transverse, vertical thin-section enlarged so to to show 

 the lamellae and the presence of a large tubule that appears to 

 have more or less imperfectly penetrated through the shell. 

 Upper Cambrian Obolus sandstone, Russia. 



