FAMILIES OF LOOP-BEARING BRACHIOPODA 297 



taken as characteristic examples. One is the Macandrevia 

 cranium Miiller, and the other has been called Magellania 

 (^Waldheimia) septigera Lovdn. In the light of the geo- 

 graphic, genetic, and ontogenetic facts, the application of 

 the law of morphogenesis necessitates a new generic name 

 for the second. Magellania cannot be retained, as the 

 type is M. venosa from Tierra del Fuego, and therefore 

 belongs to the southern line having a different series of 

 metamorphoses. Neither can it be referred to Macandrevia, 

 on account of its well-developed septum at maturity ; nor to 

 Undesia (type U. cardium Lamarck, from the Jurassic), since 

 that genus has strong dental plates in the ventral valve, divid- 

 ing the cavity of the beak into three chambers. Waagen ^^ 

 shows that these features — septal and dental plates — are 

 entitled, in the terebratuloids, to rank as generic characters. 



The name Dallina, nov. gen., is therefore proposed, to 

 include shells of the type of Terebratula septigera Lov^n ; as 

 Dallina Raphaelis Dall, sp., D. G-rayi Davidson, sp., and 

 D. fioridana Pourtales, sp. The genus is given in honor of 

 William H. Dall, whose name has long been intimately asso- 

 ciated with the best work on recent Brachiopoda. 



There still remain the northern species heretofore referred 

 to Terebratella, which differ from true Terehratella (type 

 T. dorsatci) in the same manner and degree as Dallina from 

 Magellania. These also require a special designation, and 

 the name Terebratalia, nov. gen., is proposed, based on Tere- 

 bratula transversa G. B. Sowerby, as the type. 



The earliest stages of development in the Dallina and 

 Terebratalia branch of the Terebratellidse have been observed 

 by the writer in T. transversa Sowerby and T. obsoleta Dall.* * 

 They represent first a shell without a septum in the dorsal 

 valve, and without calcified supports to the brachia (Plate 

 XIV, figure A). The structure just before the appearance 



* Originally described as Terehratella occidentaUs, var. obsoleta, by Dall, but 

 now considered by him as a distinct species. The complete development of the 

 brachial supports in this species is shown in paper No. 8 of this series. 



