2 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



A systematic presentation of the various groups of the family 

 follows : 



Family 5. LAGENID^. 



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, with a neck and phialine lip. 



The Lagenidse form one of the most distinctive groups of the 

 Foraminifera and its members are readily recognized. Usually the 

 genus Lagena, making up the subfamily Lagenidaa, has been taken as 

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

 like L. globosa probably come as near a primitive radicle for this 

 family as it is possible to determine. 



From Lagena the simplest step in development is a series of such 

 chambers as is seen in Nodosaria. On the other hand this series may 

 become, coiled as in Cristellaria. With these two genera as the base 

 all the genera of the subfamily Nodosariinse may be definitely assigned 

 to one or the other groups. With Nodosaria belong such genera as 

 Lingulina and Triplasia and with Cristellaria as reversionary forms, 

 Marginulina, Vaginulina, and Frondicularia. 



With the subfamily Polymorphininse a distinct mode of develop- 

 ment is instituted, an alternating subspiral arrangement being 

 introduced, usually accompanied by a radiate type of aperture. 



In the subfamily Uvigerininse there is again a spiral arrangement, 

 much more definite in its characters and the aperture typically has a 

 long neck and phialine lip. 



In the subfamily Ramulininse the method of growth is very irregu. 

 lar and a mass of stolon-like tubes results. 



In various genera microspheric and megalospheric forms occur 

 and as usual the microspheric form holds longest to the earlier devel- 

 opmental stages. These stages tend to show that many of the genera 

 have been derived from a coiled ancestral type, although in the 

 megalospheric form this is not so definitely shown. 



The Lagenidae are richly ornamented and the range includes costse, 

 spines, wing-like plates as well as complicated surface patterns, 

 especially well developed in the genus Lagena. The various combi- 

 nations of surface ornamentation, together with the delicacy of form 

 and curves that appear throughout the group make the Lagenidae 

 by far the most interesting of the various groups of the Foraminifera. 



x4.1though some forms are found in shallow water, the best develop- 

 ment of the Lagenidse takes place in waters from 50 to 500 fathoms 

 in depth. Lagena is found in perhaps greater numbers between 

 1,000 and 2,000 fathoms as far as the North Pacific material shows. 

 Warmer waters are necessary for the best development of Cristellaria, 

 Nodosaria, etc. 



