194 FORAMINIFERA 



Obliquina (?) Seguenza, 1. c, p. 75 (genoholotype, Obliquina acuticosta 



Seguenza). 

 Ovolina Terquem, Six. Mem. Foram. Lias, 1866, p. 473 (genotype, by 



designation, Ovolina trigonula Terquem). 

 Lcif/enulina Terquem, Essai Anim. plage Dunkerque, pt. 2, 1876, p. 67 



(genotype, by designation, Entosolenia costata Williamson). 

 Capitelliva Marsson, Mitth. Nat. Ver. Neu-Vorpommern u. Riigen, vol. 



10, 1878, p. 122 (genoholotype, Capitellina multistriata Marsson). 



Test unilocular; aperture typically radiate, rounded or ellip- 

 tical, terminal, central; wall vitreous, very finely perforate, 

 vario.usly ornamented; chambers typically v^ithout an internal 

 tube. 



Silurian to Recent. 



The Lagenidae represent one of the most variable of all the 

 groups of the foraminifera. If the early Palaeozoic records are 

 really Nodosaria, etc., the family record is one of the oldest in 

 the group. In many w^ays the entire group appears protean. 

 The genera are not clearly defined as are those of most other 

 families. It is possible in the same species from a single fossil 

 sample or recent dredge haul to find megalospheric forms refer- 

 able to Nodosaria, specimens with a small proloculum and curved 

 test referable to Dentalina, and one with a still smaller 

 proloculum coiling at the base and referable to Ma7'ginulina. 

 While Rohulus and CristeUaria may be separated in many forms 

 nevertheless there are species in which more compressed speci- 

 mens gradually lose the distinctive character of the elongated 

 specialized slit, and the aperture reverts to the equal radiate. 



So also in the Nodosarian forms there may be a very gradual 

 series from those with remote chambers and stoloniferous con- 

 nections back to ones in which the chambers are closely set, or 

 even overlapped. 



There are very many generic names that have been proposed 

 by Schubert and others for various modifications in the Lageni- 

 dae. As it is well known that the Lagenidae form one of the 

 most plastic groups of the foraminifera and that polymorphism 

 or trimorphism is present to a large extent, generic characters 

 are much harder to define than in some of the more stable 

 families. 



It is undoubtedly true that broad frondicularian chambers 

 are formed in the adults of several generic forms. Whether 

 these represent microspheric or megalospheric forms is not 



