33S FORAMINIFERA OF THE CRAG. 



impossible to indicate them in their proper order on a plane surface, such as that 

 of a sheet of paper. Varieties radiate in all directions from the type forms ; and 

 to properly indicate their relationship we should have to take a series of spiked 

 balls, like that with which the giant in the Guildhall is armed, and attach tbe 

 different varieties to these spikes at varying distances from the ball. Consequently, 

 in this table such characters as periphery, rounded or angular — chambers, few or 

 many, straight or arched — have not received the consideration due to their 

 importance. 



The side lines in the table do not indicate exactly where one type ends and 

 another begins ; one might as well try to separate the colours of the rainbow by 

 definite lines. As a rule Mr. Millett has commenced with thin forms, gradually 

 working up to the thicker ; thus, from the thin communis to the thick Labradorica, 

 from the thin umbilicatula to the thick pompilioides, and so on. 



The particulars given in this list will be sufficient for anyone who has 

 CD. Sherborn's ' Index to the Genera and Species of the Foraminifera,' except of 

 course for the figures published after a certain date (1888). Figures which are 

 merely copies are not referred to. 



The Nonionina leo of Karrer, 1868, is not included, as it might be an 

 Operculina. Nor are the very doubtful forms given by Zwingli and Kiibler 

 referred to, and very sparing use has been made of Ehrenberg's figures of 

 translucent specimens. 



Mr. Millett observes that the Polystomellse might also be treated in a similar 

 manner ; but he has not found any figure of those in which the two conditions 

 of the umbilical region are combined in one shell, as in the Gomer specimens 

 and in N. asterizans. 



Mr. Millett is inclined to think that the Anomalina punctulata, d'Orbigny 

 (' Ann. Sci. Nat.,' vol. vii, 1826, p. 282, pi. xv, figs. 1 — 3), is the " unsymmetrical " 

 form of N. incrassata (F. and M.). Before the Gomer specimens threw a light on 

 the subject, most of the unsymmetrical Nonioninx were assigned to Anomalina or 

 Truncahdina ; l and doubtless if the original specimens were now examined, many 

 species would have to be removed from one genus to the other. 



1 See, for instance, 'Ann. Mag. Nat. Hist., ser. 3, vol. iv, 1859, p. 329, where "Walker and 

 Jacob's fig. 69 is referred to Truncatulina because " the two faces are decidedly unsymmetrical." 



