FAMILY 32. ELLIPSOIDINIDAE 259 



mediate stages of which are known so that the whole is well 

 connected in all its parts. There is a tendency toward a complete 

 uniserial development. The various lines here have attained 

 them to some degree and in the Bulimininae the single chambered 

 form has been attained. The ancestral spiral form is maintained 

 in most of the genera at least in the young. The aperture of the 

 ancestral Terehraliyia, which was in the middle of the face of 

 the chamber, breaks through to the periphery but is kept as a 

 loop-shaped broader end in most of the forms. The tubular 

 siphon-like internal structure is kept in all but the most special- 

 ized forms and will serve to separate these from their similarly 

 shaped forms in other families. Species referred to Sipho- 

 generina are derived from several sources. Rectobolivina has 

 intermediate stages very clearly connecting it with species of 

 Bolivina now living in the same ocean. It is possible that some 

 of the triangular forms described as Trigonulina and here 

 referred to Lagcna may be end forms from such genera as 

 Trifarina. For a more detailed discussion of the relationships 

 in this family see Cushman, Phylogenetic Studies of the Fora- 

 minifera (Amer. Journ. Sci., vol. 13, 1927, pp. 318-321). 



The form described by H. B. Brady as Sagrina ( ?) tessellata, 

 (Challenger, 1884, p. 585, pi. 76, figs. 17-19) is a very peculiar 

 one. It was given the name of Millettia by Schubert in 1911, 

 and Schubertia by A. Silvestri in 1912. It may belong near 

 Siphogefierina, but although I have seen the original types fig- 

 ured by Brady, there is so little structure shown by the speci- 

 mens which are megalospheric that it is not possible to more 

 than guess at the actual relationships of this form. Millett 

 in his Malay work shows that the chambers have numerous 

 divisions. A study of microspheric specimens is needed to 

 obtain the developmental stages. 



FAMILY 32. ELLIPSOIDINIDAE 



Test with the wall calcareous, finely perforate, variously 

 formed, the aperture usually narrow, elongate, curved in the 

 outline of a semiellipse, a hollow tube or rod-like structure, 

 sometimes in the form of a curved plate connecting the various 

 chambers, similar in general to that found in the Buliminidae. 



