400 



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which has attained triplication (fig. 11), and the Recent well-known 

 TerebratelJa cumingi Davidson (fig. 12). Possibly also Magasella tenisoni 

 Tenison-Woods belongs here. The unity in shape of these species and 

 their distinctness from those ascribed above to Magella will be easily 

 recognized. 



Fig. 9. 



Fig. 8. 



Fig. 10. 



Fig. 8. — Magadina ivaiparensis Thomson, Mount Brown beds, Middle Waipara 



district, holotype (twice natural size). 

 Fig. 9. — Magadina cretacea (Etheridge), Gingin beds, Western Australia (after 



Etheridge), (twice natural size), a. Dorsal valve, b. Ventral valve. 



c. Interior of dorsal valve. 

 Fig. 10. — Magadina compta Sowerby, Port Fairy, Cape Otway coast, Victoria 



(after Sowerby). 



In loop characters Magadina browni is much less advanced than Magella 

 carinata, the descending and ascending branches being separately attache! 

 to the septum, which reaches to the opposite valve. This stage, termed 

 " Magadiform " by Fischer and Oehlert, differs from that of Magas in 



Fig. 11. 



Fig. 12. 



Fig. 11. — Magadina compta Tate (?of Sowerby), Mannurn, R. Murray (after 



Tate). 

 Fig. 12. — Magadina cumingi (Davidson), Backstairs Passage, South Australia 



(after specimens in the Dominion Museum supplied by Dr. Verco). 



a. Dorsal view (natural size), b. Interior of dorsal valve (enlarged). 



that the ascending branches form a complete ring, and it may now more 

 appropriately be termed "Magadiniform." Magadina cumingi possesses a 

 Magadiniform loop almost to adolescence, and finally attains an early 

 Magelliform loop. 



Magadinella gen. nov. 

 Genotype, Magasella woodsiana Tate* (fig. 13). 



The beak characters of this species are not strictly Bouchardiform, the 

 modifications being slightly greater incurvature and less sharp beak-ridges. 



* Trans. Roy. Soc. S. Austral., vol. 3 (1880), pp. 163-64, pi. x, fig. 3, a-d. 



