162 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 20 



PLATE 4 



Fig. 17. Semimytilus algosus (Gould) 1850. North Chincha Is- 

 land, Peru. Length: 28 mm. 



Fig. 18. Brachidontcs purpuratus (Lamarck) J819. Bahfa de la 

 Independencia, Peru. Length: 25 mm. 



Fig. 19. Si'ptifer bifurcatus (Conrad) 1837. Near Point Fermin, 

 California. Elongate and worn specimen. Length: 33 mm. 



Fig. 20. Sfptifer hifiircakis (Conrad) 1837. ( ? Bahia de la Inde- 

 pendencia, Peru. Label certainly wrong.) Fine regu- 

 lar form. Length 18.8 mm. 



Fig. 21. Septifer zeteki Hertlein and Strong 1946. Bahia de Gard- 

 ner, Isla Espafiola, (Hood Island), Galapagos Islands. 

 Length : 9 mm. 



