Thomson. — Brachiopod Genera. 397 



" Magadiform." These may, nevertheless, be placed in Magella, which will 

 then include all species of the Terebratella-Magellania stock which have not 

 attained at maturity the Terebratella stage of loop. Amongst such species 

 with primitive loops are Magasella australis Buckman, from the Pecten 

 conglomerate (Pleistocene) of Cockburn Island, off Graham Land, West 

 Antarctica ; Magasella gonldi Dall, from the Recent seas of Japan, which 

 is possibly only a young stage of Magellania grayi or some other species ; 

 and Magasella aleutica Dall. 



Magasella flexuosa (King), if a valid species, as Ihering contends, is 

 certainly a Magella, but it is usually considered a young stage of Terebra- 

 tella dorsata, and the same is true of Magasella patagonica (Gould). Similarly 

 Magasella (?) laevis Dall is probably the young of Magellania venosa. It is 

 probable that Terebratella woodsi Tate, from the Table Cape beds of Tas- 

 mania, and Terebratella pumila Tate, from the Gippsland Lakes, will be 

 found on dissection to belong to Magella, as they agree pretty closely with 

 the genotype in external characters. Finally, Magasella antarctica Buckman, 

 from the glauconitic bank, Cockburn Island, described by Buckman as 

 possibly the Magaselliform ancestor of Terebratella rubicunda, is without 

 doubt to be transferred here.* 



Shells with Bouchardiform Beak Characters. 



All the known species of Bouchardia, though differing somewhat in 

 length and breadth, and in the amount of ventral uniplication or unicarina- 

 tion, possess similar and rather unusual beak characters- — viz., the beak is 

 incurved only at its apex, and then but slightly ; there are sharp beak- 

 ridges uniting in front of the foramen, which is thus behind the apex, the 

 false area is prominent, and the pseudo-deltidium strong, solid, and blended 

 with the shell. These characters are illustrated in fig. 4, which comprises 

 all the known species of Bouchardia.^ 



Now, there are in New Zealand older Tertiary (Oamaruian) a series of 

 shells which bear out Buckman's dictum that " the loop may change con- 

 siderable while the shape remains little altered." These shells have Bou- 

 chardiform beak characters, and, although much larger in size, they are 

 externally so like Bouchardia that they were described as such by Hutton 

 in 1905J under the names of B. rhizoida and B. tapirina (not Waldheimia 

 tapirina Hutton, 1873). Buckman, accepting Hutton's generic determi- 

 nation, compared them with the other known species of Bouchardia, and 

 considered that in shape the New Zealand species were biologically the 

 earliest. In spite of this undoubtedly primitive shape, these specimens 

 have proved to possess Magellaniform loops and septa (fig. 5).§ It is more 



* Jackson (Trans. Roy. Soc. Edin., vol. 48 (1912), pp. 384-85) considers this species 

 the young of Terebratella dorsata, erroneously ascribing the glauconitic bank to Pleistocene, 

 whereas Buckman gives its age as Miocene -Oligocene. This greater age makes it more 

 probable that M. antarctica is an ancestral form of Terebratella dorsata than a young 

 specimen. Buckman considered it ancestral to T. rubicunda, but one would hardly 

 expect even incipient multicostation, such as M . antarctica shows, on a Miocene ancestor 

 of T. rubicunda. 



t With the exception of B. patagonica jorgensis Ihering, the original description 

 of which I have been unable to consult. 



J Trans. N.Z. Inst., vol. 37 (1905), p. 480, pi. xlvi, figs. 6, 7. The beak characters 

 are not correctly rendered in the figures. 



§ I obtained from Target Gully, Oamaru, a hollow specimen of B. rhizoida with a 

 complete loop, but unfortunately it was destroyed in removal. 



