FAMILY 45. ORBITOIDIDAE 335 



FAMILY 45. ORBITOIDIDAE 



By T. Wayland Vaughan 



Synopsis of the Family 



The following synopsis of the Orbitoididae is frankly imper- 

 fect and unsatisfactory, notwithstanding the large amount of 

 research that has been bestowed upon the family. The principal 

 workers have been Giimbel, Charles Schlumberger, Verbeek, P. 

 Lemoine and R. Douville, and H. Douville. Publications by 

 most of these authors are listed in the references under the 

 genera and subgenera of the family, and from those citations 

 most of the important literature can be found. A number of 

 Italians, especially A. Silvestri, have made important investiga- 

 tions. Recently L. Rutten, A. Tobler, F. Chapman, J. H. 

 Umbgrove, I. M. van der Vlerk, and H. Yabe have published 

 many papers on the East Indies, other Pacific Islands, Australia, 

 and Japan. W. L. F, Nuttall is the author of a series of valuable 

 articles and memoirs on the orbitoids of India. The American 

 species have received much attention from J. A. Cushman and 

 myself, and several others have published one or more articles 

 each. The most comprehensive work is that of H. Douville, 

 who has recently published a general review of the group. In 

 1924, I published a summary of what was then known of the 

 American species, a work which was confessedly tentative, 

 incomplete, and in a number of respects crude. The literature 

 is very large and it cannot be reviewed here. 



The family Orbitoididae will be defined as follows : 



Test thin or inflated, round lenticular, selliform, or stellate, 

 with a layer of equatorial chambers, which in the megalospheric 

 generation begins growth from a multilocular embryonic appar- 

 atus. Chamber walls perforate, usually also communication 

 between chambers through openings for the passage of proto- 

 plasmic stolons. There is no canal system. 



Subfamilies : 



Orbitoidinae, growth cyclical, except in very early stages 

 in which there may be, particularly in the microspheric genera- 

 tion, an initial spiral. Well developed lateral chambers on each 

 side of the equatorial layer. 



