42 



THE VOYAGE OF H.M.S. CHALLENGER 



20. " Verticordia " IwiiaUi, 



21. " Silenia" sarsi, 



22. C'vspidaria curt a, 



23. Cuspidaria fragiUssiina, 



24. Cuspidaria platensis. 

 Summary on the genera Pcfromya, "Silenia," and Cuspidaria, 



n. Comparative Part, . . . ■ • 



i. Gastropoda (Rudimentary state of the eyes), 

 ii. Pelecypoda (gills), . ■ • • 



PAGE 



20 

 22 

 23 

 23 

 23 

 25 



29 

 29 

 34 



IIL Conclusions, 



40 



