2 BULLETIN 104, UNITED STATES NATIONAL MUSEUM. 



SYSTEMATIC PART. 



A systematic presentation of the various groups of the family fol- 

 lows : 



Family 5. LAGENIDAE. 



Test calcareous, vitreous, finely perforate, either monothalamous 

 or made up of a series of chambers arranged in a straight or curved 

 axis, or close-coiled or spirally, or even in an alternating manner; 

 aperture either radiate or simple or with a neck and phialine lip. 



The Lagenidae form one of the most distinctive groups of the 

 Foraminifera and its members are readily recognized. Usually the 

 genus Lagena^ making up the subfamily Lageninae, has been taken 

 as the radicle from which the other genera have been derived. 

 Species like L. glohosa probably come as near a primitive radicle 

 for this family as it is possible to determine. 



From Lagena there is a question as to which should be considered 

 the more primitive, Nodosaina or Cristellaria. As numerous species 

 assigned to Nodosaria have in the microspheric form definite indi- 

 cations of being derived from coiled ancestry, it would seem as 

 though the coiled form, such as Cristellaria., may be the more primi- 

 tive. The genera Marginulina^ Vaginulina, and Frondicularia are 

 all evidently derived from coiled forms such as Cristellaria. Lingu- 

 lina also may have in its microspheric form a coiled series in its 

 young. This would therefore leave Nodosaria practically alone as 

 the only genus without definite coiling, but as we have already noted 

 that certain Nodosarias in their microspheric form show an arcuate 

 test and oblique sutures, it would seem to indicate that the entire 

 group is derived through originally coiled forms. 



A study of the apertures throughout the families shows an interest- 

 ing result. A few genera, such as Trifarina., Uvigerina, and Sipho- 

 generina^ have typically a test with an elongate neck and phialine 

 lip. Such a type of aperture occurs in some of the species of Nodo- 

 saria^ and occasionally elsewhere. On the other hand, most of the 

 species of Cristellaria., Vagitndina, Marginulina, Frondicularia, and 

 Polymorphiiia, with some of the species of Nodosaria, have an aper- 

 ture without an elongate neck and a radiate form as the characteristic 

 apertural distinction. Certain species of Polymorphina in their 

 senescent characters show the aperture with a neck and lip, and this 

 distinction of the apertural characters may not be of great signifi- 

 cance. In the subfamily, Polymorphininae, instead of either a 

 straight or linear series, a spiral arrangement is characteristic. In 

 the subfamily Uvigerininae a spiral arrangement is again a typical 

 character. 



